Previous Year Paper year:2011 : ICSE-X-Chemistry

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ICSE-X-Chemistry

Previous Year Paper year:2011

with Solutions - page 2

#1-c [5]
Give reason as to why:

#1-c-i
i. The electrolysis of acidulated water is considered an example of catalysis.
Ans : Sulphuric acid catalyses the ionisation of water because distilled water is a poor conductor of electricity and does not form ions.

#1-c-ii
ii. Almost 90% of all known compounds are organic in nature.
Ans : They all contains carbon as an essential component.

#1-c-iii
iii. It is dangerous to burn methane in an insufficient supply of air.
Ans : It leads to incomplete combustion releasing carbon monoxide which is extremely poisonous and cause death.

#1-c-iv
iv. Hydrogen chloride can be termed a polar covalent compound.
Ans : Difference between electronegativities of H and Cl is high. E.N. of Cl is much higher than that E.N. of H. So a unidirectional pull towards Cl will be created leading to polarity.

#1-c-v
v. The oxidising power of elements increases on moving from left to right along a
period in the periodic table.
Ans : Oxidising power means tendency to make the other element get oxidised which increases with increase in non metallic nature. From left to right in a period the non metallic nature increases.

#1-d [5]
Fill in the blanks from the choices given below:

#1-d-i
i. In covalent compounds, the bond is formed due to the_______ (sharing/transfer) of
electrons.
Ans : sharing

#1-d-ii
ii. Electrovalent compounds have _______ (low/high) boiling point.
Ans : high

#1-d-iii
iii. A molecule of _______ contains a triple bond (hydrogen, ammonia, nitrogen).
Ans : nitrogen

#1-d-iv
iv. Across a period, the ionisation potential _______ (increases, decreases, remains the
same).
Ans : increases

#1-d-v
v. Down the group, the electron affinity _______ (increases, decreases, remains the
same).
Ans : decreases

#1-e [5]

Ans :

#1-e-i
i. Calculate the volume of ``\pu{ 320 g }`` of ``\ce{SO2}`` at STP (Atomic mass: S = 32 and O = 16).

#1-e-ii
ii. State Gay-Lussac.s Law of combining volumes.