CHECKING FOR UNDERSTANDING 2020-21

Name:

1. The question consists of two statements an assertion (A) and a reason (R). To answer this question, mark the correct alternative as directed below. Assertion: After white washing the walls, a shiny white finish on walls is obtained after two to three days.Reason: Calcium oxide reacts slowly with the carbon dioxide in air to form a thin layer of calcium carbonate which gives shiny white finish to the walls.

• (A) Both A and R are true and R is the correct explanation of A.
• (B) Both A and R are true but R is not the correct explanation of A.
• (C) A is true, but R is false
• (D) A is false, but R is true.

2. The chemical formula of the white salt that produces yellow residue and releases brown fumes is:

• (A) PbNO₃
• (B) Pb₂NO₃
• (C) Pb(NO₃)₂
• (D) Pb₂(NO₃)₂

3. In which of the following, the identity of initial substance remains unchanged?

• (A) Curdling of milk
• (B) Heating of copper sulphate crystals in a dry boiling tube.
• (C) Fermentation of idli batter
• (D) Burning of natural gas

4. The reaction of quick lime in water is/are:

• (A) Endothermic reaction
• (B) Exothermic reaction
• (C) Combination reaction
• (D) Both (B)&(C)

5. The missing variables given as X,Y,Z in the chemical reaction given below are:

• (A) 2,2,3
• (B) 2,1,2
• (C) 2,2,1
• (D) 1,1,2

6. State whether the given statement is true or false.Rusting of iron and rancidity are caused due to oxidation.

• Yes
• No

7. The given equation represents the reaction of sodium metal with water. Sodium + water -----> sodium hydroxide + hydrogen Choose the balanced chemical equation for the given word equation.

• (A) Na + 2H₂O ------------------> NaOH + 2H₂
• (B) 2Na + 2H₂O -------------- ------> NaOH + 2H₂
• (C) 2Na + 2H₂O --------------------> NaOH + H₂
• (D) 2Na + 2H₂O ----------------------> 2NaOH + H₂

8. Refer to the given graph which shows the effect of pH on the activities of three enzymes, X, Y and Z. Which of the following are the possible locations in the alimentary canal of man where the three enzymes can be found?

• (A) X- Small intestine ; Y- Mouth ; Z- Stomach
• (B) X- Mouth; Y- Stomach ; Z- Small intestine
• (C) X- Stomach; Y- Small intestine ; Z- Mouth
• (D) X- Stomach; Y- Mouth ; Z- Small intestine

9. Small intestine is a site of complete digestion where different ducts get juices from gall bladder, liver and pancreas. Which diagram the correct pattern of secretion of juices?

• (A)
• (B)
• (C)
• (D)