The stomata take in and give out
(A) hydrogen.
(B) oxygen carbon dioxide, water.
(C) water and oxygen only.
(D) carbon dioxide only.

(a) Only B is correct.
(b) Only A is correct.
(c) Both B and C are correct.
(d) Both B and D are correct.

Q. Secondary sexual changes occur:
A. during puberty.
B. after menopause.
C. along with external changes.
D. only in males.

(a) Only A is correct.
(b) Both A and C are correct.
(c) Only C is correct.
(d) Both B and C are correct.

Q.

Air is a mixture of only three gasses nitrogen, oxygen and carbon dioxide.

Q. Adult frogs have
A. lungs
B. gills
C. lenticels
D. spiracles

(a) only B is correct
(b) both B and D are correct
(c) only A is correct
(d) B, C, and D are correct

Q. 1) A welding fuel gas contain carbon and hydrogen only. Burning a small sample of it in oxygen gives $3.38$ g carbon dioxide, $0.690$ g of water and no other products. A volume of $10.0L$ (measured at STP) of this welding gas is found to weigh $11.6$ g. Calculate

A) Empirical formula

2) A welding fuel gas contain carbon and hydrogen only. Burning a small sample of it in oxygen gives $3.38$ g carbon dioxide, $0.690$ g of water and no other products. A volume of $10.0$L (measured at STP) of this welding gas is found to weigh $11.6$ g. Calculate

B) Molar mass of the gas

3) A welding fuel gas contain carbon and hydrogen only. Burning a small sample of it in oxygen gives $3.38$ g carbon dioxide, $0.690$ g of water and no other products. A volume of $10.0$L (measured at STP) of this welding gas is found to weigh $11.6$ g. Calculate

C) molecular formula

Q. A welding fuel gas contains carbon and hydrogen only. Burning a small sample of it in oxygen gives 3.38 g carbon dioxide, 0.690 g of water and no other products. A volume of 10.0 L (measured at STP) of this welding gas is found to weigh 11.6 g. Choose the correct molecular formula of the gas.