C60 an allotrope of carbon contains:
18 hexagons and 14 pentagons
20 hexagons and 12 pentagons
12 hexagons and 20 pentagons
16 hexagons and 16 pentagons
B.
20 hexagons and 12 pentagons
In C60, hexagonal, 12 pentagonal
Therefore, C60 is an allotrope of carbon that consists of 20 hexagona and 12 pentagons.
Excessive release of CO2 into the atmosphere results in
depletion of ozone
polar vertex
formation of smog
global warming
Magnesium powder burns in air to give:
Mg (NO3)2 and Mg3N2
MgO and Mg3N2
MgO only
MgO and Mg(NO3)2
The given plots represent the variation of the concentration of a reactant R with time for two different reactions (i) and (ii). The respective orders of the reactions are
0, 1
0, 2
1, 0
1, 1
the correct order of the oxidation states of nitrogen in NO, N2O, NO2 and N2O3 is
NO2 < NO < N2O3 < N2O
N2O < N2O3 < NO < NO2
N2O < NO < N2O3 < NO2
NO2 < N2O3 < NO < N2O
Match the catalysts (colum I) with products (column II).
Catalyst - Column I | Products - Column II |
A. V2O5 | (i) Polyethylene |
B. TiCl4/ Al(Me)3 | (ii) Ethanal |
C. PdCl2 | (iii) H2SO4 |
D. Iron oxide | (iv) NH3 |
A - iii; B - i; C - ii; D - iv
A - ii; B - iii; C - i; D - iv
A - iv; B - iii; C - ii; D - i
A - iii; B - iv; C - i; D - ii
The aerosol is a kind of colloid in which:
Solid is dispersed in gas
liquid is dispersed in water
gas is dispersed in liquid
gas is dispersed in solid
Consider the van der walls constants, a and b, for the following gases
Gas | Ar | Ne | Kr | Xe |
a/ (atm dm6 mol-2) | 1.3 | 0.2 | 5.1 | 4.1 |
b/ (10-2 dm3 mol-1) | 3.2 | 1.7 | 1.0 | 5.0 |
Which gas is expected to have the highest critical temperature?
Kr
Ar
Ne
Xe
The ore that contains the metal in the form of fluoride is
cryolite
malachite
magnetite
Sphalerite