Threshold frequency of a metal is 5 1013 s-1 upon which 1 x 1014s-1 frequency light is focused. Then the maximum kinetic energy of emitted electron is
3.3 10-21
3.3 10-20
6.6 10-23
6.6 10-20
Arrange the following gases in order of their critical temperature.
NH3, H2O, CO2, O2
NH3 > H2O > CO2 > O2
O2 > CO2 > H2O > NH3
H2O > NH3 > CO2 > O2
CO2 >O2 >H2O > NH3
Bond dissociation energy of CH4 is 360 kJ/mol and C2H6 is 620 kJ/mol. Then bond dissociation energy of C-C bond is
170 kJ/mol
50 kJ/mol
80 kJ/mol
220 kJ/mol
pKa increases in benzoic acid when substituent "x" is bonded at para-position, then "x" is
-COOH
-NO2
-CN
-OCH3
D.
-OCH3
Larger the value of pKa smaller will be its acidity. Out of the four groups, -COOH, -NO2 and -CN are e- withdrawing which makes benzoic acid more acidic whereas -OCH3 is e- donating which reduces the acidity (makes H less easily available). pKa value increases if OCH3 is present at para-position of benzoic acid.