Chemistry/Page01

1     3.   Which metal is liquid at Room temperature(jto-lice J&K)

a)      Gold

b)      Hydrogen

c)       Silver

d)      Mercury

Ans:d

Points to be remember:

i)                    The first known super conductor is Mercury

ii)                   Mercury  flows so easily and rapid that it is sometimes called quick silver

iii)                 The highest metal is – lithium

iv)                 Mercury is the metal having lowest melting point(-39⁰C)

v)                  Liquid non-metal at room temperature is bromine

vi)                 Bromine is transparent reddish liquid that evaporate at body temperature to give an orange vapor

vii)               Metals kept under kerosene are sodium , potassium, caesium etc

viii)              The most harmful metal to human beings is lead

ix)                 the non-metal  which shows electric conductivity is Graphite(Carbon)

1.Which of the following varieties of coal has the highest  amount of carbon in it (JTO-LICE  AP     2013)

a)      Anthracite

b)      Bituminous

c)       Ligite

d)      Peat

Ans:a

Points to remember:

i)                    Carbon content   in charcoal varies with types of coal

1.       Anthracite                           90% carbon

2.       Bituminous coal                70%carbon

3.       Lignite                                   40% carbon

4.       Peat                                       10 to 15  % carbon

ii)                  Charcoal is more reactive form of carbon because of large surface area

Which   one of the following is a mixture(jto-lice AP 2013)

a)      Lime

b)      Table salt

c)       Sugar

d)      Seawater

Ans:

Air is a mixture

2.   

3.       3. Which as is green house gas

a)      Oxygen

b)      Carbon-di-oxide

c)       Nitric acid

d)      Nitrogen oxide

Ans:b

-Points to remember:

Green house gases:

i)                    Carbon di oxide (CO₂)

ii)                   Carbon monoxide(CO)

iii)                 Methane (CH₄)

iv)                 HFC(Highdrofluorocarbon),HCF(Chloroluorocarbon)
v)                  Nitrous oxide

vi)                 Sulphur Dioxide

vii)               Water vapour

4.       

11.   Which has the highest electron negativity  (Jto-lice Bihar 2013)

a)      F

b)      Cl

c)       Br

d)      I

Ans:a

Points to be remember

i)                    The electro negativity decreases down the group , increases along the period

ii)                   Power of atom to attract electron pairs.

 F     >   O    >  Cl   > N

4.00 >3.50 >3.10 >3.00

iii)           The electronegatiivity scale was discovered by Linus Pauling.