31) The gas used for artificial ripening of green fruit is ?
a)ethane
b)ethylene
c)carbon dioxide
d)acetylene
32) Air contains maximum amount of
a)oxygen
b)nitrogen
c)hydrogen
d)carbon dioxide
33) The luster of a metal is due to :
a)high polishing
b)high density
c)chemical inertness
d)presence of free electrons
34) What is laughing gas ?
a)nitrous oxide
b)nitric oxide
c)nitrogen oxide
d)nitrogen peroxide
35) The isotope atoms differ in ?
a)number of neutrons
b)atomic number
c)number of electrons
d)atomic weight
36) The nuclear particles which are assumed to hold the nucleons together are ?
a)positrons
b)neutrons
c)electrons
d)mesons
37) Chemical used in photography is
a)sodium sulphate
b)sodium sulphite
c)sodium thiosulphate
d)sodium oxalate
38) Identify the wrong statement in the following
a)Atomic radius of the elements increases as one moves down the first group of the periodic table
b)Atomic radius of the elements decreases as one moves across from left to right in the 2nd period of the
c)Amongst isoelectronic species, smaller the positive charge on the cation, smaller is the ionic radius
d)Amongst isoelectronic species, greater the negative charge on the anion, larger is the ionic radius
39) Atomic number is equal to
a)Number of electrons
b)Number of nutron
c)Number of protons
d)Total number of protons and neutrons
40) Human bone does not contain
a)calcium
b)carbon
c)oxygen
d)phosphorous