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States of Matter

Short Answer Type

171.

What are the conditions for hydrogen bonding?

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172.

Water is a liquid while hydrogen sulphide is a gas. Explain.

176 Views

173.

Out of NH₃ and PH₃, which has higher boiling point and why?

140 Views

174.

Nitrogen and chlorine have the same electronegativity but only former shows intermolecular hydrogen bonding. Discuss.

131 Views

175.
Why does ice float over water?

We know that in ice, each oxygen atom

is surrounded by four hydrogen atoms in such a way that the two hydrogen atoms are linked to an oxygen atom by covalent bonds whereas the other two hydrogen atoms are linked by hydrogen bonds. In ice (solid state), a water molecule is associated with four other water molecules through hydrogen bonding in a tetrahedral manner. This gives rise to open cage-like structure which prevents the close packing of molecules (lower density). When ice absorbs heat and melts to form water, the hydrogen bonds break and close packing of water molecules takes place. Due to this close packing, the density of water is higher than that of ice and hence ice floats over water.

595 Views

Long Answer Type

176.

Give reasons for the following:
(i) The density of water is maximum at 277 K (4°C).

(ii) Why glycerol (glycerine) is more viscous than ethyl alcohol?

308 Views

Short Answer Type

177.

Calcualte the total pressure in a mixture of 8 g of dioxygen and 4 g of dihydrogen confined in a vessel of 1 dm³at $27 degree straight C$ . R = 0.083 bar dm³ K^-1 mol^-1.

113 Views

178.

A mixture of dihydrogen and dioxygen at one bar pressure contains 20% by weight of dihydrogen. Calculate the partial pressure of dihydrogen.

132 Views

Multiple Choice Questions

179.

Which among the following gases can be liquified easily?

Chlorine
Nitrogen
Oxygen
Hydrogen

180.

If average velocity of a sample of gas molecules at 300 K is 5 cm s^-1, what is RMS velocity of same sample of gas molecules at the same temperature? (Given, α: u: v = 1:1.224: 1.127)