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Which one of the following phrases would be incorrect to use?
it will be incorrect to say that an atom of a compound because,
Every combination of atoms is a molecule. A compound is a molecule made of atoms from different elements. All compounds are molecules , but not all molecules are compounds.
Which of the following illustrates the law of conservation of mass?
Option 2 illustrates the law of conservation of mass.
The law of conservation of mass states that in a chemical reaction, the total mass of the reactants is equal to the total mass of the products. This means that matter is neither created nor destroyed in a chemical reaction.
In option 2, 12 g of CO reacts with 32 g of O2 to form 44 g of CO2. The total mass of the reactants (12 g + 32 g = 44 g) is equal to the total mass of the product (44 g). This illustrates the law of conservation of mass.
Option 1 is an example of the law of definite proportions, which states that a given compound always contains the same elements in the same proportion by mass.
Option 3 is not a valid example of the law of conservation of mass, as heating carbon in a vacuum can lead to the release of gases such as carbon dioxide, carbon monoxide, and carbon suboxide, which can escape and change the mass of the system.
Option 4 is an example of a physical change, where the state of matter of a substance changes, but the mass of the substance remains the same. It does not illustrate the law of conservation of mass.
The law of constant proportion was proposed by
In 1806, Proust summarized his observations in what is now called Proust's Law. It stated that chemical compounds are formed of constant and defined ratios of elements, as determined by mass. For example, carbon dioxide is composed of one carbon atom and two oxygen atoms.
A compound contains 8% sulphur by mass. The minimum molecular weight of the compound is:
The compound Sulphur = 8%
Therefore, 8g of S is present in 100g.
(Least molecular mass means that at least one atom of Sulphur should be present in a molecule.)
Therefore, 32g of S is peasant in 100/8 x 32 = 400
The mass of one atom of carbon-12 is
Mass of one atom = Avogadro′s numberMass of one mole of atom=12/6.02×1023
Mass of one carbon atom = 1.994×10−23g
Identify the correct one from the following statements.
option ( c) The mixture has properties similar to its compound is the correct answer.
This is because in a mixture, the constituent particles are not mixed chemically.
They are mixed physically and can be separated fairly easily by physical Methods.
Thus they show the properties of components.
Example can be alloys.
18 g of water is electrolysed. The weight of oxygen formed will be
Modern atomic symbols are based on the method proposed by
Which of the following is the chemical symbol for nitrogen gas?
N2 is the chemical symbol for nitrogen gas.
Molecular weight of CuS04. 5H20 is equal to
[Cu = 63.5 u, S = 32 u, O — 16 u, H = 1 u]
Which of the following represents a correct chemical formula?
How many moles of electrons weigh equal to one kilogram? [Mass of 1 e = 9.1 x 10-31 kg]
3.42 g sucrose are dissolved in 18 g of water in a beaker. The number of oxygen atoms in the solution are
Molar mass of sucrose = 342 g
No. of Oxygen atoms in 3.42g of (C₁₂H₂₂O₁₁) = 11 x NA
Therefore, No. of Oxygen atoms in 342g of (C₁₂H₂₂O₁₁) = 11 x Na x 3.42 / 342
= 0.11 NA
No. of oxygen atoms in 18g of H₂O = 1NA
Therefore, Total no. of Oxygen atom in 342g of Sucrose and 18g of water
= 0.11NA +1NA = 1.11NA = 1.11 x 6.02 x 10²³ ⇒ 6.68 * 1023
Arrange the following in increasing order of number of molecules.
I. 0.5 mol of H2
II. 4.0 g of H2
III. 18 g of H2O
IV 2.2 g of CO2
option ( b) is the correct✔ answer.
Explanation:- first we have to calculate, the no. of molecules and then we will compare them. To calculate the number of molecules, we multiply no. of moles with the Avagadro's number.
0.5 *( 6.022 * 10^23)
= 3.11 * 10^ 23
2* ( 6.022 * 10^23)
= 12.044 * 10^ 23
3.35 * 10^19
0.05 * ( 6.022 * 10^23)
= 0.3011 * 10^ 23
So, we can see, 4<1<3<2 is the correct✔ answer.
Which of the following symbols is incorrect?
(i) Helium (He)
(ii) Aluminium (AL)
(iii) Carbon (c)
(iv) Cobalt (CO)
Select the correct alternative:
Because , the symbol used for aluminum is Al, the symbol used for carbon is C, the symbol used for cobalt is Co.