CBSE 11TH CHEMISTRY - Online Test

Q1. When the rate of evaporation is equal to the rate of condensation, it is called
Answer : Option D
Explaination / Solution:

At equilibrium, the rate of evaporation is equal to the rate of condensation. It may be represented by H2O (l) ⇌ H2O (vap) The double half arrows indicate that the processes in both the directions are going on simultaneously. The mixture of reactants and products in the equilibrium state is called an equilibrium mixture

Q2. Physical behavior of the states differs greatly even though chemical behavior of the three states is identical because
Answer : Option C
Explaination / Solution:

chemical properties depend on intramolecular bonding forces whereas physical properties depend on intermolecular nonbonding forces

Q3. Which of these fuels given below is not a hydrocarbon?
Answer : Option B
Explaination / Solution:

Because hydrocarbons contain both C and H and hence Hydrogen is not a hydrocarbon. .

Q4. Mendeleev 'Periodic Law' states that
Answer : Option B
Explaination / Solution:

If the elements are arranged in the order of their increasing atomic weights, after a regular interval similiar properties of elements are repeated.

Q5. In a closed system, Which of the following take place ?
Answer : Option A
Explaination / Solution:

In a closed system, there is no flow of matter from system to surrounding or vice versa. For example, a certain quantity of fluid bounded within a closed cylinder constitutes a closed system.

Q6. Cathode rays or cathode ray particles are
Answer : Option D
Explaination / Solution:

Cathode rays - In 1897, British physicist J. J. Thomson showed the rays were composed of a previously unknown negatively charged particle, which was later named the electron.

Q7. The effect of undesirable changes in the environment causing harm to living beings is termed as:
Answer : Option B
Explaination / Solution:

Environmental pollution is the harmful effect of undesirable changes caused by substances of chemical, biological or human origin.

Q8. Hydrogen is the first element in the periodic table and has resemblance to alkali metals as well as with halogens. However, its placement in the periodic table has been a subject of discussion in the past. Currently hydrogen is placed in which group?
Answer : Option A
Explaination / Solution:

H properties matches with alkali metal as well as halogens so it is placed separately

Q9. Matter can be classified at the macroscopic or bulk level as


Answer : Option C
Explaination / Solution:

At macroscopic level matter is classified as mixture or pure substances .A mixture contains two or more components (in any ratio ) present in it , for example -- sugar solutions in water , tea , air , alloys like brass ,bronze etc. Pure substances (viz. copper , silver , gold , water , glucose etc . ) have fixed composition . The constituents of pure substances can not be separated by simple physical methods.

Q10. Inertness of noble gas was observed to be due to their electronic configurations: Choose the most appropriate
Answer : Option B
Explaination / Solution:

The six noble gases (Helium Neon Argon Krypton Xenon Radon) are found in group 18 of the periodic table. These elements were considered to be inert gases until the 1960's, because their oxidation number of 0 prevents the noble gases from forming compounds readily. All noble gases have the maximum number of electrons possible in their outer shell (2 for Helium, 8 for all others), making them stable.