sblock Elements - Result Question 15
####11. The correct statements among (a) to (d) regarding $H _2$ as a fuel are :
(2019 Main, 11 Jan I)
I. It produces less pollutants than petrol.
II. A cylinder of compressed dihydrogen weights $\sim 30$ times more than a petrol tank producing the same amount of energy.
III. Dihydrogen is stored in tanks of metal alloys like $NaNi _5$.
IV. On combustion, values of energy released per gram of liquid dihydrogen and LPG are 50 and $142 kJ$, respectively.
(a) I, II and III only
(b) II, III and IV only
(c) II and IV only
(d) I and III only
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Answer:
Correct Answer: 11. (b)
Solution:
- (I) $H _2$ is a $100 %$ pollution free fuel. So, statement (I) is correct.
(II) Molecular weight of $H _2(2 u)$.
$=\frac{1}{29} \times$ molecular weight of butane,
$C _4 H _{10}$ (LPG) [58u].
So, compressed $H _2$ weighs $\sim 30$ times more than a petrol tank and statement (II) is correct.
(III) $NaNi _5, Ti-TiH _2$ etc. are used for storage of $H _2$ in small quantities. Thus, statement (III) is correct.
(IV) On combustion values of energy released per gram of liquid dihydrogen $\left(H _2\right): 142 kJ g^{-1}$, and for LPG : $50 kJ g^{-1}$. So, staement (IV) is incorrect.
