Question

16.
Which of the following is/are staple libro(s)?
AS Silk
(C) Wool
(B) Cotton
(D) Both (B) and (C)
17.
Which of the following is NOT a causing factor in acid rain?
(A) Carbon dioxide
(B) Sulphur dioxide
Yes Silicon dioxide
(D) Nitrogen dioxide
18
Which of the following statements is false?
(A) Burning of candle wax is a physical as well as chemical change,
(B) For rusting presence of both water and oxygen is essential.
e) The burning of kerosene is a reversible change.
(D) Rusting of iron can be provented by depositing a layer of zinc or chromium on it.
Which of the following is NOT a mineral acid?
(A) HCI
(C) HNOS
(B) H2SO4
(D) HCOOH
20.
Which of the following statements is INCORRECT?
(A) Humus is a non-living organic matter.
(B) Sandy soil has the lowest percolation rate of water.
(C) The most fertile layer of soil is the A-horizon
(D) Clayey soil is mainly used for making pots and toys.
21.
On heating, a solid gets directly converted into gaseous state. This change is called
(A) Evaporation
(B) Sublimation
(C) Fusion
YD) Diffusion​

Answer 1

1. silk
2. Silicon dioxide
3. the burning kerosene is a reversible change
4. matlab are the most fertile layer of soil is A- horizen
5. sublimation