Chemistry (Part-II)

Total Questions: 54

1. Which one of the following molecules is linked by a double covalent bond? [S.S.C. Online CHSL (T-I) 8.02.2017]

Correct Answer: (b) 0₂
Solution:In oxygen gas (O₂), two oxygen atoms can complete an octet (8 electrons) in the outermost orbital by sharing two electrons per oxygen atom to obtain a stable electron configuration. So in O₂, a double covalent bond is formed.

2. The residual attractive or repulsive forces between molecules or atomic groups that do not arise from a covalent or ionic bond is called: [S.S.C. Online CHSL (T-I) 23.01.2017]

Correct Answer: (d) Van der Walls bond
Solution:

Van der Waals forces are defined as the residual attractive or repulsive forces between molecules or atomic groups that do not arise from a covalent bond or electrostatic interactions of ions or ionic groups.

These forces are weaker than covalent and ionic bonds and include various types of intermolecular interactions, such as London dispersion forces, dipole-dipole interactions, and dipole-induced dipole interactions.

3. Two or more elements combine chemically in a certain proportion to form a new substance called: [S.S.C. Online Stenographer 13.09.2017]

Correct Answer: (b) compound
Solution:A compound is a substance formed when two or more different chemical elements are chemically bonded together in a fixed ratio. These bonds can be covalent or ionic.

4. What is the bond angle (in degrees) in the structure of a Benzene molecule? [S.S.C. Online Graduate Level(T-I) 7.03.2020]

Correct Answer: (b) 120
Solution:

The benzene molecule (C₆H₆) has a planar hexagonal ring structure. Each carbon atom in the ring is bonded to two other carbon atoms and one hydrogen atom. The carbon atoms are hybridized, resulting in bond angles of 120 degrees.
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5. Which among the following compounds has the strongest Hydrogen bond? [S.S.C. Online CHSL (T-I) 17.01.2017]

Correct Answer: (c) HF
Solution:

Hydrogen fluoride (HF) has the strongest hydrogen bonds compared to HI, HCl, and HBr, because the combined fluorine in HF is the most electronegative element.

Due to the high electronegativity of fluorine, the HF molecule has a strong dipole moment, leaving a positive (+) charge on the hydrogen and a negative (-) charge on the fluorine atom.

Hence, the HF molecules are joined by hydrogen bonding to each other. That is why hydrogen fluoride is found in the liquid state at room temperature, while other halides vaporize.

6. Which among the following will be a negative ion? [S.S.C. Online CHSL (T-I) 11.01.2017]

Correct Answer: (a) If it has more electrons than protons
Solution:

Protons are positively charged particles found in the nucleus of an atom. The number of protons defines the element.

Electrons are negatively charged particles that orbit the nucleus. In a neutral atom, the number of electrons equals the number of protons,  resulting in no net charge.

Neutrons are neutral particles found in the nucleus. They contribute to the atom's mass but not its charge.

When an atom gains one or more electrons, it has more negative charges (electrons) than positive charges (protons), resulting in a net negative charge. This negatively charged atom is called a negative ion or an anion.

7. Atomic number of which of the following elements is greater than that of Calcium? [S.S.C. Online CHSL (T-I) 7.02.2017]

Correct Answer: (d) Scandium
Solution:

Calcium (Ca): Atomic number is 20.
Chlorine (Cl): Atomic number is 17.
Argon (Ar): Atomic number is 18.
Sulphur (S): Atomic number is 16.
Scandium (Sc): Atomic number is 21.
Comparing the atomic numbers, we can see that Scandium (atomic number 21) has an atomic number greater than Calcium (atomic number 20).
Therefore, the answer is Scandium.

8. The chemical nature of an element depends on which of the following? [S.S.C. Online Stenographer 13.09.2017]

Correct Answer: (c) On Valence electron
Solution:The chemical nature of an element depends on the valence electrons of the elements. The valence electron of an element is the electron present in the outer shell of that element, which helps in forming a bond with another element.

9. Which of the following is a weak electrolyte? [S.S.C. Online Stenographer 13.09.2017]

Correct Answer: (a) Ethanoic acid
Solution:Ethanoic acid is a weak electrolyte because it does not completely ionize in an aqueous solution. This is due to covalent bonds whereas sodium chloride (NaCl) etc. are strong electrolytes because they are completely ionized.

10. .............. is a polar covalent bond. [S.S.C. Online CHSL (T-I) 19.01.2017]

Correct Answer: (a) P-Cl
Solution:

P-Cl (phosphorus chlorine) is a polar covalent bond. Chlorine is more electronegative than phosphorus, meaning it has a stronger attraction for electrons.

This unequal sharing of electrons results in a partial negative charge on the chlorine atom and a partial positive charge on the phosphorus atom, making the bond polar and the resulting compound polarized.