1. Which of the following statements is not correct ?
(a). Pure para hydrogen can be obtained by cooling ordinary hydrogen to about 20 K.
(b). The ratio of ortho and para hydrogen at 300 K and above is 3 : 1.
(c). The ratio of ortho to para hydrogen varies with temperature.
(d). Pure ortho hydrogen can be obtained by heating ordinary hydrogen above 300 K.
2. The ionisation energy value of Li,H and F are 520,1312 and 1680 kJ mol-1 . Which of the following could be a consequence of the above ?
(a). Hydrogen forms large number of covalent bonds like halogens.
(b). Hydrogen exists as a gas at room temperature.
(c). Hydrogen has 1s1 configuration.
(d). Both (a) and (b).
211)-d(the percentage of ortho hydrogen can never be more than 75%.)
2)-d
4At standard temperature and pressure, hydrogen gas contains about 25% of the
para form and 75% of the ortho form, also known as the "normal form" --> (b)
At very low temperatures, the equilibrium state is composed almost exclusively of the para
form. ---> (a)
From (a) & (b) , (c) is also obviously correct
Therefore ans is (d)
4(2) (c) is not a consequence though it's true
(b) is true since the inter molecular forces r responsible for them being gases and inturn
ionisation energy is responsible for IMF
(a) Hydrogen is covalently bonded in almost all its compounds. This is mainly because its ionisation energy is very high, so the formation of H+ is not favoured. Also, H+ is a proton and so is extremely small, and this small size gives it exceptionally strong polarising power
So I go with d
29For second question i think only A is correct..
@ Saket , Arka and Uttara
can u explain how B is correct
11] d
2] hydrogen exist as a gas at room temperature, hw dis can b consequence of ionisation potential? plz do solve my dbt, so i think for this one ans is only [a]
