Basic chemistry questions for practice

A good grasp over science concepts will help you have a crack at the competitive exams. These practice questions focusing on general science will aid aspirants to prepare better for the State government recruitment examinations. 1. Which of the following quantum numbers is not necessary to identify an orbital? a) Principal quantum number b) Azimuthal […]

A good grasp over science concepts will help you have a crack at the competitive exams.
These practice questions focusing on general science will aid aspirants to prepare better for the State government recruitment examinations.

1. Which of the following quantum numbers is not necessary to identify an orbital?
a) Principal quantum number
b) Azimuthal quantum number
c) Magnetic quantum number
d) Electron Spin quantum number
Ans: d
Explanation: An orbital is identified by the set of 3 quantum numbers: Principal quantum number, Azimuthal quantum number and magnetic quantum number.

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2. Which of the following is correct about Photoelectric effect?
a) Number of electrons ejected is twice the wavenumber of radiation
b) Number of electrons ejected is proportional to the intensity of light
c) Number of electrons ejected is proportional to the duration of light
d) Number of electrons ejected is not dependent on the intensity of light
Ans: b
Explanation: The phenomenon of ejection of electrons from the surface of metal when light of suitable frequency strikes is called photoelectric effect. The number of electrons ejected is proportional to the intensity or brightness of light.

3. Which of the following factors affect the rate of chemical reaction?
a) Concentration of reactants b) Temperature
c) Catalyst d) All of the above
Ans: d
Explanation: The rate of reaction depends upon the experimental conditions such as concentration of reactants (pressure in case of gases), temperature and catalyst.

4. Which of the following is a part of Chalcogen group of the modern periodic table?
a) Boron b) Tin c) Lead d) Oxygen
Ans: d
Explanation: The Chalcogens are the group 16 elements of the periodic table. This group is also known as the oxygen family. It consists of the elements Oxygen (O), Sulphur (S), Selenium (Se), Tellurium (Te), and the radioactive element Polonium (Po).

5. Choose the correct statement about d-block elements:
a) These are the elements of Group 3 to 10 b) All of them are metals
c) Both a and b d) None
Ans: b
Explanation: d-block elements are the elements of Group 3 to 12 in the centre of the periodic table. All of them are metals. These are characterised by the filling of inner d orbitals by electrons.

6. What is the shape of SF4 molecule?
a) Bent b) See-saw
c) Trigonol Pyramidal d) T-shape
Ans: b
Explanation: SF4 molecule is in See-saw shape. It has 4-bonding pairs of electrons and one lone pair of electrons.

7. Which of the following gases is liberated when a metal reacts with an acid?
a) Oxygen b) Hydrogen c) Carbon dioxide d) Nitrogen
Ans: b
Explanation: The metal displaces hydrogen from the acids. This is seen as hydrogen gas. The metal combines with the remaining part of the acid and forms a compound called a salt.

For more questions, visit the TS BC Study Circles Telegram group https://t.me/ Ukk7l_n7wJxmMjll.

To be continued…
By K Aloke Kumar
Director,
Telangana State BC Study Circles