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All questions of Chemical Combination for JAMB Exam
What is the amount of water produced when 8g of hydrogen is reacted with 32g of oxygen?- a)2moles
- b)1mole
- c)3 moles
- d)0.5mole
Correct answer is option 'A'. Can you explain this answer?
What is the amount of water produced when 8g of hydrogen is reacted with 32g of oxygen?
a)
2moles
b)
1mole
c)
3 moles
d)
0.5mole
|
Sun Ray Institute answered |
The chemical equation of water formation is 2H2 + O2 → 2H2O. Though we have 8g of hydrogen, here oxygen is the limiting reagent. So the only 4g of hydrogen can be used to produce water i.e. 36g of water. That is 2 moles.
Which of the following is not true regarding balanced chemical equations?- a)They contain the same number of atoms on each side
- b)Electrons are also balanced
- c)An equal number of molecules on both the side
- d)Follows the law of conservation of mass
Correct answer is option 'C'. Can you explain this answer?
Which of the following is not true regarding balanced chemical equations?
a)
They contain the same number of atoms on each side
b)
Electrons are also balanced
c)
An equal number of molecules on both the side
d)
Follows the law of conservation of mass
|
Efehuan Ekpe answered |
Understanding Balanced Chemical Equations
Balanced chemical equations are crucial in chemistry, as they represent the conservation of mass during reactions. However, not all statements regarding them are true.
Key Features of Balanced Equations:
- Same Number of Atoms:
- Balanced equations ensure that the number of each type of atom is the same on both sides of the equation. This reflects the principle of conservation of mass.
- Electrons are Balanced:
- In redox reactions, electron transfer is balanced to maintain charge neutrality. However, this is not explicitly shown in simple chemical equations focused on mass balance.
- Equal Number of Molecules:
- This is where the misconception lies. Balanced equations do not necessarily have an equal number of molecules on both sides. The coefficients in front of compounds may differ, reflecting the varying amounts of reactants and products.
- Law of Conservation of Mass:
- The law states that matter cannot be created or destroyed in a chemical reaction. Balanced equations uphold this law by ensuring that the total mass of reactants equals the total mass of products.
Conclusion:
The correct answer to the original question is option 'C' because balanced equations focus on atom and charge balance, not necessarily on having the same number of molecules on each side. Understanding this distinction is essential for accurately interpreting chemical reactions.
Balanced chemical equations are crucial in chemistry, as they represent the conservation of mass during reactions. However, not all statements regarding them are true.
Key Features of Balanced Equations:
- Same Number of Atoms:
- Balanced equations ensure that the number of each type of atom is the same on both sides of the equation. This reflects the principle of conservation of mass.
- Electrons are Balanced:
- In redox reactions, electron transfer is balanced to maintain charge neutrality. However, this is not explicitly shown in simple chemical equations focused on mass balance.
- Equal Number of Molecules:
- This is where the misconception lies. Balanced equations do not necessarily have an equal number of molecules on both sides. The coefficients in front of compounds may differ, reflecting the varying amounts of reactants and products.
- Law of Conservation of Mass:
- The law states that matter cannot be created or destroyed in a chemical reaction. Balanced equations uphold this law by ensuring that the total mass of reactants equals the total mass of products.
Conclusion:
The correct answer to the original question is option 'C' because balanced equations focus on atom and charge balance, not necessarily on having the same number of molecules on each side. Understanding this distinction is essential for accurately interpreting chemical reactions.
One mole of sucrose contains how many grams of sucrose?- a)342g
- b)343g
- c)341g
- d)340g
Correct answer is option 'A'. Can you explain this answer?
One mole of sucrose contains how many grams of sucrose?
a)
342g
b)
343g
c)
341g
d)
340g
|
Chikaodi Okeke answered |
Understanding Molar Mass of Sucrose
To determine how many grams one mole of sucrose weighs, we need to understand the concept of molar mass. Sucrose, commonly known as table sugar, has the chemical formula C12H22O11.
Calculating Molar Mass
To find the molar mass, we sum the atomic masses of all the atoms in one molecule of sucrose:
- Carbon (C): 12 atoms × 12.01 g/mol = 144.12 g/mol
- Hydrogen (H): 22 atoms × 1.008 g/mol = 22.176 g/mol
- Oxygen (O): 11 atoms × 16.00 g/mol = 176.00 g/mol
Now, adding these values together:
- Total = 144.12 g/mol + 22.176 g/mol + 176.00 g/mol
- Total = 342.296 g/mol
Since molar mass is typically rounded to a reasonable number of significant figures, we can approximate this to 342 g/mol.
Conclusion
Thus, one mole of sucrose weighs approximately 342 grams.
- The correct answer is option 'A' (342 g).
- This value is crucial for stoichiometric calculations in chemistry, especially in reactions involving sucrose.
Understanding the molar mass of compounds like sucrose is essential for accurately measuring quantities in laboratory settings and for various applications in food science and nutrition.
To determine how many grams one mole of sucrose weighs, we need to understand the concept of molar mass. Sucrose, commonly known as table sugar, has the chemical formula C12H22O11.
Calculating Molar Mass
To find the molar mass, we sum the atomic masses of all the atoms in one molecule of sucrose:
- Carbon (C): 12 atoms × 12.01 g/mol = 144.12 g/mol
- Hydrogen (H): 22 atoms × 1.008 g/mol = 22.176 g/mol
- Oxygen (O): 11 atoms × 16.00 g/mol = 176.00 g/mol
Now, adding these values together:
- Total = 144.12 g/mol + 22.176 g/mol + 176.00 g/mol
- Total = 342.296 g/mol
Since molar mass is typically rounded to a reasonable number of significant figures, we can approximate this to 342 g/mol.
Conclusion
Thus, one mole of sucrose weighs approximately 342 grams.
- The correct answer is option 'A' (342 g).
- This value is crucial for stoichiometric calculations in chemistry, especially in reactions involving sucrose.
Understanding the molar mass of compounds like sucrose is essential for accurately measuring quantities in laboratory settings and for various applications in food science and nutrition.
Which of the following is not a law of chemical combination?- a)Law of Multiple Proportions
- b)Avogadro’s Law
- c)Law of Definite Proportion
- d)Law of Conservation of volume
Correct answer is option 'D'. Can you explain this answer?
Which of the following is not a law of chemical combination?
a)
Law of Multiple Proportions
b)
Avogadro’s Law
c)
Law of Definite Proportion
d)
Law of Conservation of volume
|
|
Sun Ray Institute answered |
Five basic laws are required to govern the combination of elements to form compounds. They are Law of Conservation of Mass, Law of Definite Proportions, Law of Multiple Proportions, Gay Lussac’s Law of Gaseous Volumes, and Avogadro’s Law.
Which of the given reactions are counted as balanced reactions?- a)H2 + O2 → 2H2O
- b)4Al + 3O2 → 2Al2O3
- c)Mg(OH)2 + 2HNO3 → 2Mg(NO3)2 + 2H2O
- d)N2 + 3H2 → NH3
Correct answer is option 'B'. Can you explain this answer?
Which of the given reactions are counted as balanced reactions?
a)
H2 + O2 → 2H2O
b)
4Al + 3O2 → 2Al2O3
c)
Mg(OH)2 + 2HNO3 → 2Mg(NO3)2 + 2H2O
d)
N2 + 3H2 → NH3
|
|
Sun Ray Institute answered |
4Al + 3O2 → 2Al2O3 is a balanced reaction because the number of atoms of different elements on both sides is equal. The correctly balanced equations of the rest are 2H2 + O2 → 2H2O; Mg(OH)2 + 2HNO3 → Mg(NO3)2 + 2H2O and N2 + 3H2 → 2NH3.
The elements, Unnilhexium and Seaborgium are the same.- a)True
- b)False
Correct answer is option 'A'. Can you explain this answer?
The elements, Unnilhexium and Seaborgium are the same.
a)
True
b)
False
|
|
Sun Ray Institute answered |
Unnilhexium is the 106th element as per IUPAC nomenclature, as the roots are un, nil, and hex which means 1, 0 and 6. The 106th element’s official name is Seaborgium. Seaborgium is a synthetic element that is named after Glenn T. Seaborg.
The volumes of hydrogen & oxygen when combined bear a simple ratio of 2:1.This is explained by ________- a)Law of Multiple Proportions
- b)Avogadro’s Law
- c)Law of Definite Proportion
- d)Gay Lussac’s Law of Gaseous Volumes
Correct answer is option 'D'. Can you explain this answer?
The volumes of hydrogen & oxygen when combined bear a simple ratio of 2:1.This is explained by ________
a)
Law of Multiple Proportions
b)
Avogadro’s Law
c)
Law of Definite Proportion
d)
Gay Lussac’s Law of Gaseous Volumes
|
|
Sun Ray Institute answered |
When gases combine or as written in a chemical reaction they combine in a simple ratio by volume, provided that all gases are at the same temperature and given pressure, this is called Gay Lussac’s Law of Gaseous Volumes and is proposed by Joseph Louis.
Which of the following statement is correct?- a)The value of Avogadro’s number is 6.022×1022 atoms
- b)One molecule of any substance contains Avogadro’s number of particles
- c)One mole is the amount of a substance that contains as many particles as there are atoms in exactly 12 g of the carbon atom
- d)1 u is not equal to Ma/NA
Correct answer is option 'C'. Can you explain this answer?
Which of the following statement is correct?
a)
The value of Avogadro’s number is 6.022×1022 atoms
b)
One molecule of any substance contains Avogadro’s number of particles
c)
One mole is the amount of a substance that contains as many particles as there are atoms in exactly 12 g of the carbon atom
d)
1 u is not equal to Ma/NA
|
|
Sun Ray Institute answered |
The corrected statements are as follows: the value of Avogadro’s number is 6.022×1023 atoms, one molecule of any substance contains Avogadro’s number of particles & 1 u = Ma/NA. The correct option is that one mole is the amount of a substance that contains as many particles as there are atoms in exactly 12 g of the carbon atom.
In a particular reaction, one of the reactants limits the number of products formed. That is called as _______- a)Limiting reagent
- b)Limiting product
- c)Excessive reagent
- d)Excessive reactant
Correct answer is option 'A'. Can you explain this answer?
In a particular reaction, one of the reactants limits the number of products formed. That is called as _______
a)
Limiting reagent
b)
Limiting product
c)
Excessive reagent
d)
Excessive reactant
|
|
Sun Ray Institute answered |
Though the other substances are excess in amount than the required, each and every reactant needs to be in a fixed ratio to attain the desired product. So, thereby, the reactant that limits the quantity of the product formed is called limiting reagent and this reactant gets consumed first completely.
What did Joseph Proust state regarding Law of Definite Proportions?- a)A given mixture always contains absolutely the same proportion of elements by weight
- b)A given compound always contains absolutely the same proportion of moles by weight
- c)A given compound always contains absolutely the same proportion of elements by volume
- d)A given compound always contains absolutely the same proportion of elements by weight
Correct answer is option 'D'. Can you explain this answer?
What did Joseph Proust state regarding Law of Definite Proportions?
a)
A given mixture always contains absolutely the same proportion of elements by weight
b)
A given compound always contains absolutely the same proportion of moles by weight
c)
A given compound always contains absolutely the same proportion of elements by volume
d)
A given compound always contains absolutely the same proportion of elements by weight
|
|
Sun Ray Institute answered |
When Joseph Proust worked about the composition of elements present in a compound experimentally, he found out that it was the same for all the samples he took. Joseph Louis concluded that from any source, a particular compound always contains the same elements in the same proportion by mass/weight.
A solution contains 8 moles of solute and the mass of the solution is 4 kg. What’s the molality of this solution?- a)5 mol/kg
- b)8 mol/kg
- c)4 mol/kg
- d)0.5 mol/kg
Correct answer is option 'D'. Can you explain this answer?
A solution contains 8 moles of solute and the mass of the solution is 4 kg. What’s the molality of this solution?
a)
5 mol/kg
b)
8 mol/kg
c)
4 mol/kg
d)
0.5 mol/kg
|
|
Sun Ray Institute answered |
Molality of a solution is given y the formula; molality = number of moles of the solute/mass of the solution. So here the number of moles is 8 and the mass of the solution is 4 kg. Molality is 8/4 = 0.5 mol/kg.
Calculate the mass percent of magnesium in the formation of magnesium oxide.- a)0.3
- b)1.5
- c)0.67
- d)0.6
Correct answer is option 'D'. Can you explain this answer?
Calculate the mass percent of magnesium in the formation of magnesium oxide.
a)
0.3
b)
1.5
c)
0.67
d)
0.6
|
|
Sun Ray Institute answered |
The chemical equation of formation of magnesium oxide is 2 Mg(s) + O2(g) ® 2MgO(s). The formula for calculation of mass percent is (mass of solute/mass of solution) x 100. Therefore 2(24)/2(24+16) = 0.6.
What’s the balanced equation of CO2 + H2O → C6H12O6 + O2?- a)CO2 + H2O → C6H12O6 + O2
- b)6 CO2 + 6 H2O → C6H12O6 + 6 O2
- c)6 CO2 + 6 H2O → C6H12O6 + 2 O2
- d)3 CO2 + 2H2O → C6H12O6 + O2
Correct answer is option 'B'. Can you explain this answer?
What’s the balanced equation of CO2 + H2O → C6H12O6 + O2?
a)
CO2 + H2O → C6H12O6 + O2
b)
6 CO2 + 6 H2O → C6H12O6 + 6 O2
c)
6 CO2 + 6 H2O → C6H12O6 + 2 O2
d)
3 CO2 + 2H2O → C6H12O6 + O2
|
|
Sun Ray Institute answered |
6 CO2 + 6 H2O → C6H12O6 + 6 O2 is the balanced equation because the number of atoms of different elements is the same on both sides. Rest of them do not have an equal number of atoms of different elements on both sides.
Which of the following may be an incorrect statement?- a)Law of Definite Composition is also known as Law of Definite composition
- b)Mass can neither be created nor destroyed is Law of Conservation of Volume
- c)Antoine Lavoisier conducted many experiments regarding combustion
- d)Five basic laws are required to govern the combination of elements to form compounds
Correct answer is option 'B'. Can you explain this answer?
Which of the following may be an incorrect statement?
a)
Law of Definite Composition is also known as Law of Definite composition
b)
Mass can neither be created nor destroyed is Law of Conservation of Volume
c)
Antoine Lavoisier conducted many experiments regarding combustion
d)
Five basic laws are required to govern the combination of elements to form compounds
|
|
Sun Ray Institute answered |
The correct statement is mass can neither be created nor destroyed is the Law of Conservation of Mass. On conducting many experiments regarding combustion and noticing various physical and chemical changes, there is no change in overall mass hence conservation of mass.
Which of the following is not the name of the 104th element?- a)Rutherfordium
- b)Kurchatovium
- c)Unnilquadium
- d)Neptunium
Correct answer is option 'D'. Can you explain this answer?
Which of the following is not the name of the 104th element?
a)
Rutherfordium
b)
Kurchatovium
c)
Unnilquadium
d)
Neptunium
|
|
Sun Ray Institute answered |
For claiming credit for discovering 104th element, the Americans named it Rutherfordium and the Soviets named it Kurchatovium. While it’s named Unnilquadium as per IUPAC nomenclature. Neptunium is the 93rd element.
What’s the atomic number of the element Copernicium?- a)111
- b)112
- c)113
- d)114
Correct answer is option 'B'. Can you explain this answer?
What’s the atomic number of the element Copernicium?
a)
111
b)
112
c)
113
d)
114
|
|
Sun Ray Institute answered |
The element of Copernicium’s atomic number is 112. it is otherwise called as Ununbium as per the IUPAC nomenclature. The name Copernicium is given after the astronomer Nicolaus Copernicus. It’s a d-block transactinide element that belongs to Group-12.
According to S.I. the system, ______ was used to measure the amount of substance.- a)mole
- b)weight machine
- c)weight
- d)mass
Correct answer is option 'A'. Can you explain this answer?
According to S.I. the system, ______ was used to measure the amount of substance.
a)
mole
b)
weight machine
c)
weight
d)
mass
|
|
Sun Ray Institute answered |
One mole is the amount of a substance that contains as many particles as there are atoms in exactly 12 g of the carbon atom. So S.I. the system took mole as the seventh base fundamental quantity (symbol = mol).
1 u = Ma/NA.- a)True
- b)False
Correct answer is option 'A'. Can you explain this answer?
1 u = Ma/NA.
a)
True
b)
False
|
|
Sun Ray Institute answered |
In the above given equation 1 u = Mu/NA; “u” refers to the atomic mass unit, Mu refers to molar mass constant(Its value is defined to be 1 g/mol in SI units). 1 u = Ma/NA = 1.660539040 x 10-27 kg. Hence the above statement is true.
Who proposed that equal volumes of all gases at the same temperature & given pressure should contain an equal number of molecules?- a)Antoine Lavoisier
- b)Joseph Proust
- c)Avogadro
- d)Joseph Louis
Correct answer is option 'C'. Can you explain this answer?
Who proposed that equal volumes of all gases at the same temperature & given pressure should contain an equal number of molecules?
a)
Antoine Lavoisier
b)
Joseph Proust
c)
Avogadro
d)
Joseph Louis
|
|
Sun Ray Institute answered |
Avogadro’s law is an experimental gas law combining & relating the volume of a gas to the amount of substance of gas present i.e’ directly proportional. This law is valid only for ideal gases. And also only when the pressure and temperature of the given substance are constant.
What’s the name of the 109th element as per the nomenclature?- a)Unnilennium
- b)Unnilunium
- c)Ununnillium
- d)Ununennium
Correct answer is option 'A'. Can you explain this answer?
What’s the name of the 109th element as per the nomenclature?
a)
Unnilennium
b)
Unnilunium
c)
Ununnillium
d)
Ununennium
|
|
Sun Ray Institute answered |
As per IUPAC nomenclature, 0 – nil, 1 – un, 2 – bi, 3 – tri, 4 – quad, 5 – pent, 6 – hex, 7 – sept, 8 – oct and 9 – enn. Here it’s 109 so 1 – un, 0 – nil and 9 – enn, combining them its unnilennium (adding “-ium” after it).
What are the roots of 1, 1, and 9 respectively as per the IUPAC nomenclature, and find out its symbol?- a)un, bi, and quad; Ubq
- b)nil, bi, and sept; Ubs
- c)un, un, and enn; Uue
- d)un, bi, and enn; Ube
Correct answer is option 'C'. Can you explain this answer?
What are the roots of 1, 1, and 9 respectively as per the IUPAC nomenclature, and find out its symbol?
a)
un, bi, and quad; Ubq
b)
nil, bi, and sept; Ubs
c)
un, un, and enn; Uue
d)
un, bi, and enn; Ube
|
|
Sun Ray Institute answered |
As per IUPAC nomenclature, the roots are as follows: 0 – nil, 1 – un, 2 – bi, 3 – tri, 4 – quad, 5 – pent, 6 – hex, 7 – sept, 8 – oct and 9 – enn. So the roots for 1, 1 and 9 are un, un, and enn. Hence the symbol of the elements is Uue.
A mole of any substance contains _______- a)6.022 x 1026 particles
- b)6.022 x 1022 particles
- c)6.022 x 1023 particles
- d)3.022 x 1022 particles
Correct answer is option 'C'. Can you explain this answer?
A mole of any substance contains _______
a)
6.022 x 1026 particles
b)
6.022 x 1022 particles
c)
6.022 x 1023 particles
d)
3.022 x 1022 particles
|
|
Sun Ray Institute answered |
The answer is Avogadro’s number. One mole of any substance contains Avogadro’s number of particles. Avogadro number denoted by NA. Its value is 602213670000000000000000, also written as 6.022×1023.
A and B are two solutions that are mixed. Calculate the resultant solution’s molarity.
- a)0.8 mol/L
- b)0.88 mol/L
- c)1.3 mol/L
- d)1.05 mol/L
Correct answer is option 'B'. Can you explain this answer?
A and B are two solutions that are mixed. Calculate the resultant solution’s molarity.
a)
0.8 mol/L
b)
0.88 mol/L
c)
1.3 mol/L
d)
1.05 mol/L
|
|
Sun Ray Institute answered |
Step 1: Calculate the total moles of solute in solution A
Moles of A = Molarity of A × Volume of A (in liters)
Moles of A = 1.3 mol/L × 0.1 L = 0.13 mol
Moles of A = Molarity of A × Volume of A (in liters)
Moles of A = 1.3 mol/L × 0.1 L = 0.13 mol
Step 2: Calculate the total moles of solute in solution B
Moles of B = Molarity of B × Volume of B (in liters)
Moles of B = 0.8 mol/L × 0.5 L = 0.4 mol
Moles of B = Molarity of B × Volume of B (in liters)
Moles of B = 0.8 mol/L × 0.5 L = 0.4 mol
Step 3: Calculate the total moles of solute in the mixture
Total moles = Moles of A + Moles of B
Total moles = 0.13 mol + 0.4 mol = 0.53 mol
Total moles = Moles of A + Moles of B
Total moles = 0.13 mol + 0.4 mol = 0.53 mol
Step 4: Calculate the total volume of the mixture
Total volume = Volume of A + Volume of B
Total volume = 0.1 L + 0.5 L = 0.6 L
Total volume = Volume of A + Volume of B
Total volume = 0.1 L + 0.5 L = 0.6 L
Step 5: Calculate the molarity of the mixture
Molarity of mixture = Total moles ÷ Total volume
Molarity of mixture = 0.53 mol ÷ 0.6 L = 0.883 mol/L
Molarity of mixture = Total moles ÷ Total volume
Molarity of mixture = 0.53 mol ÷ 0.6 L = 0.883 mol/L
Hence, The molarity of the resultant solution is 0.883 mol/L.
12.044 x 1023 atoms of oxygen contains _______- a)1 mole of oxygen
- b)2 moles of oxygen
- c)3 moles of oxygen
- d)4 moles of oxygen
Correct answer is option 'B'. Can you explain this answer?
12.044 x 1023 atoms of oxygen contains _______
a)
1 mole of oxygen
b)
2 moles of oxygen
c)
3 moles of oxygen
d)
4 moles of oxygen
|
|
Sun Ray Institute answered |
One mole of any substance contains Avogadro’s number of particles. Its value is 6.022×1023 atoms. But here it’s given 12.044 x 1023 atoms, thereby dividing it by Avogadro’s number; 12.044 x 1023 atoms/6.022×1023 atoms = 2 moles. Hence it contains 2 moles of oxygen.
If one mole of ammonia contains “y” number of particles, then how many particles do 1 mole of glucose contain?- a)2y
- b)0.5y
- c)3y
- d)y
Correct answer is option 'D'. Can you explain this answer?
If one mole of ammonia contains “y” number of particles, then how many particles do 1 mole of glucose contain?
a)
2y
b)
0.5y
c)
3y
d)
y
|
|
Sun Ray Institute answered |
Let it be any compound, but one mole of a substance always contains Avogadro’s number of particles. In the above question, Avogadro’s number (6.022×1023) is given by the letter “y”. so, in 1 mole of glucose, there is y number of particles.
In a container, there are 4 moles of nitrogen, 3 moles of oxygen and 7 moles of hydrogen; find out the mole fraction of oxygen in this reaction.- a)0.2143
- b)0.2142
- c)0.1234
- d)0.2434
Correct answer is option 'A'. Can you explain this answer?
In a container, there are 4 moles of nitrogen, 3 moles of oxygen and 7 moles of hydrogen; find out the mole fraction of oxygen in this reaction.
a)
0.2143
b)
0.2142
c)
0.1234
d)
0.2434
|
|
Sun Ray Institute answered |
Mole fraction of a substance is given by the formula: Mole fraction = No. of moles of that substances/No. of total moles of solution. Mole fraction of oxygen here = 3/4 + 3 + 7 = 3/14 = 0.2143.
What is the atomic number of the element unniloctium?- a)106
- b)118
- c)108
- d)116
Correct answer is option 'C'. Can you explain this answer?
What is the atomic number of the element unniloctium?
a)
106
b)
118
c)
108
d)
116
|
|
Sun Ray Institute answered |
As per IuPAC nomenclature of periodic elements greater than 100, Un means 1, nil means 0 and oct means 8, so the element numbered 108 is unniloctium. It’s chemical names is Hassium and is represented by the symbol “Hs”. It is highly radioactive in nature and man made.
For the 115th element _________ is the name as per IUPAC nomenclature and __________ is the official name.- a)Unnilquadium, Mendelevium
- b)Unnilunium, Rutherfordium
- c)Ununpentium, Moscovium
- d)Moscovium, Ununpentium
Correct answer is option 'C'. Can you explain this answer?
For the 115th element _________ is the name as per IUPAC nomenclature and __________ is the official name.
a)
Unnilquadium, Mendelevium
b)
Unnilunium, Rutherfordium
c)
Ununpentium, Moscovium
d)
Moscovium, Ununpentium
|
|
Sun Ray Institute answered |
As per IUPAC nomenclature, the roots are as follows: 0 – nil, 1 – un, 2 – bi, 3 – tri, 4 – quad, 5 – pent, 6 – hex, 7 – sept, 8 – oct and 9 – enn. So 115 is Ununpentium and the official name is Moscovium was named after the Moscow Oblast in which Joint Institute for Nuclear Research is situated.
Law of Definite Composition is also known as ________- a)Law of Multiple Proportions
- b)Avogadro’s Law
- c)Law of Definite Proportion
- d)Law of Conservation of Mass
Correct answer is option 'C'. Can you explain this answer?
Law of Definite Composition is also known as ________
a)
Law of Multiple Proportions
b)
Avogadro’s Law
c)
Law of Definite Proportion
d)
Law of Conservation of Mass
|
|
Sun Ray Institute answered |
Joseph Proust worked about the composition of elements present in a compound experimentally, he concluded that from any source, a particular compound always contains the same elements in the same proportion by mass/weight. Hence it can also be known as the Law of Definite Proportion.
What’s the symbol of the element Unnilquadium?- a)Unl
- b)Unq
- c)Uns
- d)Ubn
Correct answer is option 'B'. Can you explain this answer?
What’s the symbol of the element Unnilquadium?
a)
Unl
b)
Unq
c)
Uns
d)
Ubn
|
|
Sun Ray Institute answered |
Unnilquadium is a combination of un, nil, and quad i.e. 1, 0 and 4 as per IUPAC nomenclature. Its symbol is formed by joining the first letters. So combining u from uni, n from nil and q from quad, we get Unq.
What did Dalton propose?- a)Law of Multiple Proportions
- b)Avogadro’s Law
- c)Law of Definite Composition
- d)Law of Conservation of Mass
Correct answer is option 'A'. Can you explain this answer?
What did Dalton propose?
a)
Law of Multiple Proportions
b)
Avogadro’s Law
c)
Law of Definite Composition
d)
Law of Conservation of Mass
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Sun Ray Institute answered |
Two or more elements those are given, may combine to form more than one compound, the masses of one element that will combine with the given mass of the other elements, would be in the ratio of whole numbers is the law of Multiple Proportions.
Find the amount of carbon dioxide produced by the combustion of 20g of methane.- a)44g
- b)20g
- c)66g
- d)22g
Correct answer is option 'C'. Can you explain this answer?
Find the amount of carbon dioxide produced by the combustion of 20g of methane.
a)
44g
b)
20g
c)
66g
d)
22g
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Sun Ray Institute answered |
The chemical balanced equation for combustion of methane is CH4(g) + 2O2(g) →CO2(g) + 2H2O(g). From the above equation, 1 mole of methane gives 1 mole of carbon dioxide. But 20g of methane = 1.25 moles, therefore it gives 1.25 moles of carbon dioxide = 44(1.5) = 66g.
In olden days, as a privilege to the discoverer, the elements were named as they suggested by IUPAC.- a)True
- b)False
Correct answer is option 'A'. Can you explain this answer?
In olden days, as a privilege to the discoverer, the elements were named as they suggested by IUPAC.
a)
True
b)
False
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Sun Ray Institute answered |
Traditionally, IUPAC ratified the name selected by the discoverer. But later this led to the problem because the synthesis of these elements required costly equipment and laboratory as the elements with higher atomic numbers are highly unstable.
What’s the number of particles in 10 moles of hydrochloric acid?- a)6.022 x 1022 particles
- b)6.022 x 1023 particles
- c)6.22 x 1023 particles
- d)3.22 x 1022 particles
Correct answer is option 'A'. Can you explain this answer?
What’s the number of particles in 10 moles of hydrochloric acid?
a)
6.022 x 1022 particles
b)
6.022 x 1023 particles
c)
6.22 x 1023 particles
d)
3.22 x 1022 particles
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Sun Ray Institute answered |
One mole of any substance contains Avogadro’s number of particles. Its value is 6.022×1023 atoms. But here the question is about 10 moles of a substance. So multiply the Avogadro’s number by 10. Therefore 6.022×1023 x 10 = 6.022×1022.
The element ____________ is also known as Unnilunium.- a)Nobelium
- b)Mendelevium
- c)Hassium
- d)Flerovium
Correct answer is option 'B'. Can you explain this answer?
The element ____________ is also known as Unnilunium.
a)
Nobelium
b)
Mendelevium
c)
Hassium
d)
Flerovium
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Sun Ray Institute answered |
As per the notations of the IUPAC nomenclature, the 101st element is named as Unnilunium. When the Einstenium was bombarded with alpha particles, Mendelevium was discovered and named after Dmitri Mendeleev.
What’s the number of entities or particles together in mole concept known as?- a)Boltzmann constant
- b)Avogadro’s number
- c)Universal gas constant
- d)Reynold’s number
Correct answer is option 'B'. Can you explain this answer?
What’s the number of entities or particles together in mole concept known as?
a)
Boltzmann constant
b)
Avogadro’s number
c)
Universal gas constant
d)
Reynold’s number
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Sun Ray Institute answered |
Avogadro number denoted by NA. Its value is 602213670000000000000000, also written as 6.022×1023. It’s the number of entities in 1 mol of a substance. The units may be electrons, atoms, ions, or molecules, depending on the nature of the substance.
Who proposed Law of Conservation of Mass?- a)Antoine Lavoisier
- b)Joseph Proust
- c)Lorenzo Romano
- d)Joseph Louis
Correct answer is option 'A'. Can you explain this answer?
Who proposed Law of Conservation of Mass?
a)
Antoine Lavoisier
b)
Joseph Proust
c)
Lorenzo Romano
d)
Joseph Louis
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Sun Ray Institute answered |
Antoine Lavoisier conducted many experiments regarding combustion and noticed various physical and chemical changes and there is no change in overall mass. Hence he came to a conclusion that mass can neither be created nor destroyed i.e. Law of Conservation of Mass.
Who proposed the Law of Definite Composition?- a)Joseph Proust
- b)Lorenzo Romano
- c)Joseph Louis
- d)Antoine Lavoisier
Correct answer is option 'A'. Can you explain this answer?
Who proposed the Law of Definite Composition?
a)
Joseph Proust
b)
Lorenzo Romano
c)
Joseph Louis
d)
Antoine Lavoisier
|
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Sun Ray Institute answered |
Joseph Proust worked about the composition of elements present in a compound experimentally, he concluded that from any source, a particular compound always contains the same elements in the same proportion by mass/weight.
1 mole of ammonia is of 17 g. Then what is the mass of 0.3 moles of ammonia?- a)21g
- b)5.1g
- c)17g
- d)1g
Correct answer is option 'B'. Can you explain this answer?
1 mole of ammonia is of 17 g. Then what is the mass of 0.3 moles of ammonia?
a)
21g
b)
5.1g
c)
17g
d)
1g
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Sun Ray Institute answered |
To find the mass of 0.3 moles of ammonia (NH₃), use the concept of molar mass:
- Molar mass of ammonia = 17 g/mol
- Mass = moles × molar mass
- Mass of 0.3 moles = 0.3 moles × 17 g/mol
- Mass = 5.1 g
- Thus, the mass of 0.3 moles of ammonia is 5.1 g.
- Therefore, the correct answer is B: 5.1 g.
How many basic laws are required to govern the combination of elements to form compounds?- a)6
- b)5
- c)4
- d)1
Correct answer is option 'B'. Can you explain this answer?
How many basic laws are required to govern the combination of elements to form compounds?
a)
6
b)
5
c)
4
d)
1
|
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Sun Ray Institute answered |
Five basic laws are required to govern the combination of elements to form compounds. They are Law of Conservation of Mass, Law of Definite Proportions, Law of Multiple Proportions, Gay Lussac’s Law of Gaseous Volumes, and Avogadro’s Law.
Chapter doubts & questions for Chemical Combination - Chemistry for JAMB 2025 is part of JAMB exam preparation. The chapters have been prepared according to the JAMB exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for JAMB 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
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Chemistry for JAMB
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