Catalyst is a substance that increases the rate of reaction and the process is known as catalysis. Berzelius coined the term ’catalyst’ in 1835. Catalysts affect the forward and backward reactions equally so they do not alter the value of the equilibrium constant. They do not take part in the reaction and remain unchanged. If a substance decreases the rate of reaction it is known as an inhibitor. A catalyst works by forming a transient intermediate complex, which eventually decomposes forming product and the catalyst is regained back.
1. Which of the following is incorrect for a catalyst?
(a) Bio-chemical reactions are mostly catalysed by enzymes
(b) Catalyst does not start a reaction
(c) Catalyst changes the equilibrium constant of a reaction
(d) Co-enzymes increase the activity of an enzyme
Answer: (c)
2. How does a catalyst increase the rate of a reaction?
(a) By forming an intermediate complex
(b) By increasing activation energy
(c) By lowering the activation energy
(d) By changing equilibrium constant
Answer: (c)
3. Which of the following is used as a catalyst in the contact process?
(a) V2O5
(b) Fe2O3
(c) Ag2O
(d) SO3
Answer: (a)
4. Which of the following is known as Lindlar’s catalyst?
(a) Na in liquid NH3
(b) Pt in ethanol
(c) Pd with BaSO4
(d) Ni in ethanol
Answer: (c)
5. Which of the following enzymes catalyses the hydrolysis of triglycerides to fatty acids and glycerol?
(a) Pepsin
(b) Maltase
(c) Zymase
(d) Lipase
Answer: (d)
6. Ziegler Natta catalyst is associated with
(a) polymerisation of alkenes
(b) hydrogenation of alkenes
(c) hydroformylation of alkenes
(d) none of the above
Answer: (a)
7. What is the effect of enzymes on the rate of biochemical reactions?
(a) The rate increases
(b) It does not change
(c) The rate decreases
(d) either (b) or (c)
Answer: (a)
8. Which of the following is used as a catalyst in the lead chamber process?
(a) Nitrogen oxides
(b) Pt
(c) Ni
(d) V2O5
Answer: (a)
9. Which of the following is changed in a chemical reaction due to a catalyst?
(a) Internal energy
(b) Entropy
(c) Enthalpy
(d) Activation energy
Answer: (d)
10. Which of the following is incorrect for enzymes?
(a) Enzymes are specific
(b) Most of the enzymes are protein
(c) Reactivity of enzymes is least at optimum temperature
(d) High temperature and UV rays can denature enzymes
Answer: (c)
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