CBSE 11TH CHEMISTRY - Online Test
Q1. One of the following options is not used for explaining atomic radius
Answer : Option D
Explaination / Solution:
The distance from centre of the nucleus to the outermost shell containing the electrons is called atomic radius. There are four types that are widely used: covalent radii, metallic radii, van der Waal's radii and ionic radii.
Q2. Radio frequency region of the electromagnetic spectrum is used for broadcasting. It is
Answer : Option D
Explaination / Solution:
Radio frequency (RF) is any of the electromagnetic wave frequencies that lie in the range extending from around3 kHz to 300 GHz, which include those frequencies used in radio communication or radar. RF usually refers to electrical rather than mechanical oscillations
Q3. Chemical species present in the environment are either naturally occurring or generated by human activities. Their interrelation with the surroundings is called :
Answer : Option A
Explaination / Solution:
environmental chemistry basically deals with the interrelationship between chemical species generated by human activities or naturally.
Q4. In Calgon’s method, one of the following chemical is used to remove hardness of water
Answer : Option C
Explaination / Solution:
Sodium hexametaphosphate is called calgon. Its molecular formula is (NaPO3)6 or Na6P6O18.
The addition of Calgon to hard water causes the calcium and magnesium ions of hard water to displace sodium ions from the anion of Calgon. This results in the removal of calcium and magnesium ions from hard water in the form of a complex with Calgon. The water is softened and sodium ions are released into water.
Q5. Enthalpies of formation of CO(g), , and are -110, –-393, 81 and 9.7 kJ respectively. Find the value of for the reaction:
Answer : Option C
Explaination / Solution:
Q6. Among the following the maximum covalent character is shown by the compound
Answer : Option A
Explaination / Solution:
Few ionic bonds have partial covalent characteristics which were first discussed by a scientist, Kazimierz Fajans in 1923. He gave the rule to predict whether a chemical bond will be covalent or ionic which is now commonly known as Fajan’s rule. The rule can be stated as:
- Size of the ion: Smaller the size of cation, larger the size of anion, greater is the covalent character of the ionic bond.
- Charge of Cation: Greater the charge of cation, greater is the covalent character of the ionic bond.
- Electronic configuration- For cations with same charge and size, the one, with (n-1)dnns0 which is found in transition elements have greater covalent character than the cation with ns2np6 electronic configuration, which is commonly found in alkali or alkaline earth metals.
Keeping these rules in mind, we can say that AlCl3 has high covalent character.
Q7. Choose the correct order of increase in electopositivity of alkaline earth metals in the options given below
Answer : Option D
Explaination / Solution:
As we move down the group size increases so IE value decreases thus electropositivity also decreases.( shielding effect also decreases as we go down the Group)
Q8. The technique that is extensively used to separate mixtures into their components, purify compounds and also to test the purity of compounds is
Answer : Option A
Explaination / Solution:
Chromatography is used to separate mixtures of substances into their components. All forms of chromatography work on the same principle. They all have a stationary phase (a solid, or a liquid supported on a solid) and a mobile phase (a liquid or a gas).
Q9. Calculate the total number of electrons present in 1.4 g of dinitrogen gas.
Answer : Option C
Explaination / Solution:
molesofN2=1.428=0.05molAnd1moleofN2=6.022×1023moleculesofN2And1moleculeofN2has14electronstotalnumberofelectronsin1.4gofN2=0.5×6.022×1023×14=4.214×1023
Q10.
On increasing the pressure, in which direction will the gas phase reaction proceed to re-establish equilibrium is predicted by applying the Le Chatelier’s principle. Consider the reaction. (g) Which of the following is correct, if the total pressure at which the equilibrium is established, is increased without changing the temperature?
Answer : Option D
Explaination / Solution:
is independent of P change ,only the position at which equilibrium will be established will differ.
