http://i63.tinypic.com/4vprp1.jpg - Question 1 why is the answer (a)..?

1.
A. True
Calcium oxide does not react with gas X, because both of them are basic. Hence, calcium oxide can be used as the drying agent.
As gas X is less dense than air, it can be collected by upward delivery (or downward displacement of air).

B. False
As gas X is less dense than air, it CANNOT be collected by downward delivery (or upward displacement of air).

C. False
As gas X is soluble in water to form an alkaline solution, it CANNOT be collected over water.

D. False
Gas X is alkaline, and thus it can be absorbed by the concentrated sulfuric acid in neutralization. Therefore, sulfuric should NOT be used as the drying agent.

...... The answer is : A