Usa Is the Best Country

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PAKTURK INTERNATIONAL SCHOOLS & COLLEGES
ISLAMABAD

SUBJECT:CHEMISTRY MARKS: 25
CLASS:10-O Level TIME: 35 min.
Solve all three questions on answer sheet . Neat presentation would be appreciated. Q.No.1:
The figure below represents a section of catalytic converter. Catalytic converters are used in car exhaust to reduce air pollution.

[pic]

(a) (i)name substance X.[1]
(ii) What is the purpose of putting X in the catalytic converter?[1] (b)Y contains a mixture of gases. Name three gases present in Y which are (i)affected by X.
(ii)not affected by X.[3]
(c)Z contains another mixture of gases. Name two gases in Z which are produced by chemical reaction as Y passes through the catalytic converter.[2] (d)Write word equations for the two reactions that take place in catalytic converter.[2]

Q.No.2:

Carbon dioxide is a greenhouse gas. Carbon dioxide is given a greenhouse factor of 1. Other gases are given a greenhouse factor that compares their effect with carbon dioxide. The greenhouse effect increases as the factor value increases. The table gives the information about four different gases.

|gas |Greenhouse |Percentage of gas in atmosphere | | |factor | | |CO2 |1 |0.036 | |CH4 |30 |0.0017 | |N2O |160 |0.00030 | |CCl3F |21000 |0.000000028 |

a) State one possible consequence of greenhouse effect.[1]

b) Why is an increase in the percentage of methane more worrying than the same percentage...
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