Q1.In order to decide what course the reaction adopts and make a qualitative prediction about the effect of a change in conditions on equilibrium we use
Answer : Option DExplaination / Solution:
Le Chaterlier principle is used.
Q2.A catalyst increases the rate of the chemical reaction for the conversion of reactants to products by
Answer : Option CExplaination / Solution:
A catalyst increases the rate of the chemical reaction by making available a new low energy pathway for the conversion of reactants to products. It increases the rate of forward and reverse reactions that pass through the same transition state and does not affect equilibrium. Catalyst lowers the activation energy for the forward and reverse reactions by exactly the same amount. Catalyst does not affect the equilibrium composition of a reaction mixture. It does not appear in the balanced chemical equation or in the equilibrium constant expression.
Q4.The solutions which resist change in pH on dilution or with the addition of small amounts of acid or alkali
Answer : Option CExplaination / Solution:
The solutions which resist change in pH on dilution or with the addition of small amounts of acid or alkali are called Buffer Solutions. Buffer solutions of known pH can be prepared from the knowledge of pKa of the acid or pK b of base and by controlling the ratio of the salt and acid or salt and base. A mixture of acetic acid and sodium acetate acts as buffer solution around pH 4.75 and a mixture of ammonium chloride and ammonium hydroxide acts as a buffer around pH 9.25.X`
Answer : Option AExplaination / Solution:
Ice and water kept in a perfectly insulated thermos flask (no exchange of heat between its contents and the surroundings) at 273K and the atmospheric pressure are in equilibrium state and the system shows interesting characteristic features. We observe that the mass of ice and water do not change with time and the temperature remains constant.
Q9.When hydrochloric acid is added to cobalt nitrate solution at room temperature, the following reaction takes place and the reaction mixture becomes blue. On cooling the mixture it becomes pink. On the basis of this information mark the correct answer. [Co (H2O)6]3+(aq)+ 4Cl−(aq) [CoCl4]2−(aq)+ 6H2O(l )
Answer : Option CExplaination / Solution:
This reaction is endothermic.
Q10.The pH of neutral water at 25∘C is 7.0. As the temperature increases, ionisation of water increases, however, the concentration of H+ ions and OH− ions are equal. What will be the pH of pure water at 60∘C?
Answer : Option CExplaination / Solution: pH of water will be around 7 only. Water will be neutral even at 60°C
Total Question/Mark :
Scored Mark :
Mark for Correct Answer : 1
Mark for Wrong Answer : -0.5
Mark for Left Answer : 0