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Atomic number of the element which is surrounded by elements with atomic numbers 17, 34, 36 and 53 in the modern periodic table is
  • a)
    18
  • b)
    35
  • c)
    37
  • d)
    52
Correct answer is option 'B'. Can you explain this answer?

Ashwin Saha answered
The atomic number of an element represents the number of protons in the nucleus of an atom of that element. In the modern periodic table, elements are arranged in order of increasing atomic number. Based on the information given, we can determine the atomic number of the element surrounded by elements with atomic numbers 17, 34, 36, and 53.

Identify the elements:
- The atomic number 17 corresponds to chlorine (Cl).
- The atomic number 34 corresponds to selenium (Se).
- The atomic number 36 corresponds to krypton (Kr).
- The atomic number 53 corresponds to iodine (I).

Determine the missing element:
To find the missing element, we need to look for an element that fits between atomic numbers 34 and 36. The atomic number 35 corresponds to the element bromine (Br). Therefore, bromine is the element surrounded by elements with atomic numbers 17, 34, 36, and 53.

The correct answer is option 'B' (35).

What type of oxide would Eka-aluminium form?
  • a)
    EO3
  • b)
    E2O3
  • c)
    E3O2
  • d)
    EO
Correct answer is option 'B'. Can you explain this answer?

Ashwini dubey answered
Understanding Eka-Aluminium and Its Oxide Form
Eka-aluminium, known as Gallium (Ga), is a chemical element that belongs to the group of metals in the periodic table. It is important to understand how it reacts and what kind of oxides it forms.
Oxide Formation in Gallium
Gallium typically forms oxides in specific ratios, and the most common oxide it produces is Ga2O3.
Reason for the Answer (E2O3)
- Valency of Gallium:
- Gallium has a valency of +3, which means it can lose three electrons to form compounds.
- Combining with Oxygen:
- Oxygen typically has a valency of -2. To balance the charges, two Gallium atoms (each with a +3 charge) will combine with three oxygen atoms (each with a -2 charge).
- Chemical Formula Derivation:
- The ratio of Gallium to Oxygen in the oxide is thus 2:3, leading to the formula Ga2O3, which corresponds to option E2O3.
Other Options Explained
- EO3: This would imply a different valency not applicable to Gallium.
- E3O2: This would suggest a higher ratio of Gallium, which is not stable.
- EO: Represents a 1:1 ratio, which is also incorrect for Gallium.
Conclusion
Given the chemical properties and valency of Gallium, the oxide it forms is best represented by the formula E2O3, confirming option 'B' as the correct answer.

Three elements B, Si and Ge are
  • a)
    metals
  • b)
    non-metals
  • c)
    metalloids
  • d)
    metal, non-metal and metalloid, respectively
Correct answer is option 'C'. Can you explain this answer?

Pranita mehta answered
**Explanation:**

The elements B (Boron), Si (Silicon), and Ge (Germanium) are all located in Group 14 of the periodic table.

**1. Metalloids:**

Metalloids are elements that have properties of both metals and non-metals. They are located along the zigzag line on the periodic table, separating the metals from the non-metals.

**Boron (B):**
- Boron is a metalloid element.
- It is a non-metallic element that is typically brittle in its pure form.
- Boron is a poor conductor of electricity but can act as a semiconductor at high temperatures.
- It has properties of both metals and non-metals, making it a metalloid.

**Silicon (Si):**
- Silicon is a metalloid element.
- It is the second most abundant element in the Earth's crust and is widely used in the technology industry.
- Silicon has a shiny, metallic appearance but is a poor conductor of electricity at room temperature.
- It is used extensively in the production of computer chips and other electronic devices.
- Like boron, silicon has properties of both metals and non-metals, classifying it as a metalloid.

**Germanium (Ge):**
- Germanium is also a metalloid element.
- It has a similar shiny, metallic appearance to silicon.
- Germanium is a semiconductor and has useful electrical properties.
- It is used in transistors, solar cells, and other electronic applications.
- Similar to boron and silicon, germanium exhibits properties of both metals and non-metals, making it a metalloid.

Therefore, the correct answer is option **C) metalloids**, as all three elements B, Si, and Ge are metalloids.

Elements A, B and C Constitute a Dobereiner’s triad. If the atomic mass of element A is 7 and that of element C is 39, then what is the atomic mass of element B?
  • a)
    23
  • b)
    46
  • c)
    22
  • d)
    32
Correct answer is option 'A'. Can you explain this answer?

A, B and C are the elements of a Dobereiner's triad. If the atomic masses of A and C are 7 and 39 respectively, then according to Dobereiner's triad law, the atomic mass of B is the average of the atomic masses of A and C.
So, the average of the atomic masses of A and C 

Therefore, the atomic mass of B is 23.

Which of the following does not increase while moving down the group of the periodic table?
  • a)
    Atomic radius
  • b)
    Valence
  • c)
    Metallic character
  • d)
    Number of shells in on element
Correct answer is option 'B'. Can you explain this answer?

Ritu Saxena answered
In a group valency of all elements is fixed because of having the same outer shell electronic configuration while all the remaining three properties increase down the group.

Which one of the following elements exhibit maximum number of valence electrons?
  • a)
    Na
  • b)
    P
  • c)
    Al
  • d)
    Si
Correct answer is option 'B'. Can you explain this answer?

Vivek Bansal answered
  • Electronic configuration of Na, Al, Si and P are 2, 8 1, 2, 8, 3, 2, 8, 4, and 2, 8, 5 respectively. 
  • Valence electrons in Na, Al, Si and P are 1,3,4 and 5.
  • Hence phosphorus has maximum number of valence electrons.

The elements A, B, C, D and E have atomic number 9, 11, 17, 12 and 13 respectively. Which pair of elements belong to the same group?
  • a)
    A and C
  • b)
    A and D
  • c)
    A and E
  • d)
    B and D
Correct answer is option 'A'. Can you explain this answer?

Ritu Saxena answered
Let us take a look at the electronic configurations of the given elements, 
A: (2, 7)
B: (2, 8, 1) 
C: (2, 8, 7)
D: (2, 8, 2)
E: (2, 8, 3)
We can see that elements A and C both have 7 valence electrons. Thus, both the elements belong to the same group.
So, the correct option is A.

Which of the following elements would lose an electron easily?
  • a)
    Na
  • b)
    Mg
  • c)
    Ca
  • d)
    K
Correct answer is option 'D'. Can you explain this answer?

Larger the atomic radius of an element, more easily it can lose its valence electrons. K has the largest atomic radius, therefore it can lose on electron more easily.

Which of the following gives the correct increasing order of the atomic radii of O, F and N?
  • a)
    F, O, N
  • b)
    O, F, N
  • c)
    N, F, O
  • d)
    O, N, F
Correct answer is option 'A'. Can you explain this answer?

Radha Iyer answered
Atomic radius decreases across a period because nuclear charges increase across a period. When the charge increases, the electrons are pulled towards the nucleus with greater force decreasing the size of the atomic radius. Hence Fluorine has the least radius as its atomic number is larger than oxygen and nitrogen. The same case is with oxygen, it has more number of positive charges than nitrogen. Hence nitrogen has the largest size than oxygen and then fluorine.

The two elements for which Mendeleev left blank places in his original periodic table were
  • a)
    Al, Ga
  • b)
    As, Sb
  • c)
    Ga, Ge
  • d)
    Si, Ti
Correct answer is option 'C'. Can you explain this answer?

Rohit Sharma answered
  • Though only 63, elements were known at the time when Mendeleev started his work, he left some places vacant for elements to be discovered later.
  • While developing his Periodic Table of the elements,he named aka-Aluminum to the element just below of Aluminium.
  • Mendeleev gave the name eka-Aluminium to a compound which contains aluminium, a mixture of aluminium and an unknown element.
  • The unknown element he predicted would have properties similar to those of aluminium and which have rare isotope of aluminium.
  • It was later discovered as Gallium with an atomic weight of 68 and atomic number of 31.
  • Germanium was named as Aka-Silicon first and was later discovered.
  • Germanium has atomic number 32 and an atomic weight of 72.
Hence, Mendeleev left the gaps for the elements with predicted atomic weight 68 & 72 respectively are discovered later as Gallium & Germanium.

Which of the following elements does not lose an electrons easily?
  • a)
    Na
  • b)
    Mg
  • c)
    Al
  • d)
    F
Correct answer is option 'D'. Can you explain this answer?

Elements of 2nd period have smaller size than those of the corresponding elements of the 3rd period. Further is a period, halogen has the smallest size. Among Na, F, Mg and Al, F has the smallest size and hence it does not lose an electron easily.

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