Answer
(a) false
(b) true
(c) false
(d) false
Work Step by Step
(a)As the formula of water is $H_2O$ . This shows that there are two hydrogen and one oxygen atom per molecule of water. Molar of oxygen is 16 and that of two hydrogen atoms is 2. Thus the given statement is false because the mass of hydrogen is less than oxygen, not twice.
(b) As the formula of water molecule is $H_2O$ so there are two hydrogen and one oxygen atom. Hence, the given statement formula is true.
(c) From $H_2O$, we calculate the mass of oxygen as 16 and that of hydrogen as 2. 16:2 gives 8:1. Thus the given statement is false.
(d) The given statement is false because there no two oxygen atoms and one hydrogen atom; instead there are two hydrogen atoms and one oxygen atom as the formula of water molecule is $H_2O$
