The number of hydrogen atoms present in 25.6 g of sucrose (C₁₂H₂₂O₁₁) which has a molar mass of 342.3 g is

• 22 $\times$ 10²³

• 9.91 $\times$ 10²³

• 11 $\times$ 10²³

• 44 $\times$ 10²³ H atoms

The oxidation number of oxygen in KO₃, Na₂O₂ is

• 3, 2

• 1, 0

• 0, 1

• -0.33, -1

The number of formula units of calcium fluoride, CaF₂ present in 146.4 g of CaF₂ (the molar mass of CaF₂is 78.08 g/mol) is

• 1.129 $\times {10}^{24} {\mathrm{CaF}}_2$

• 1.146 $\times {10}^{24} {\mathrm{CaF}}_2$

• 7.808 $\times {10}^{24} {\mathrm{CaF}}_2$

• $1.877 \times {10}^{24} {\mathrm{CaF}}_2$

4.

The standard free energy change of a reaction is $∆\mathrm{G}°= -115 \mathrm{kJ} \mathrm{at} 298 \mathrm{K}.$ Calculate the equilibrium constant K_p in log K_p (R =8.314 JK ^-1mol^-1 ).

• 20.16

• 2.303

• 2.016

• 13.83

If an endothermic reaction occurs spontaneously at constant temperature (T) and pressure (p), then which of the following is true?

• $∆\mathrm{G} > 0$

• $∆\mathrm{H} < 0$

• $∆\mathrm{S} > 0$

• $∆S < 0$

A spontaneous process is one in which the system suffer

• no energy change

• a lowering of free energy

• a lowering of entropy

• an increase in internal energy

${\mathrm{CH}}_3{\mathrm{CH}}_3 + {\mathrm{HNO}}_3 \stackrel{675\mathrm{K}}{\to } ?$

• CH₃CH₂NO₂

• CH₃CH₂NO₂ + CH₃NO₂

• 2CH₃NO₂

• CH₂$=$ CH₂

Diamond is hard because

• all the four valence electrons are bonded to each carbon atoms by covalent bonds

• it is a giant molecule

• it is made up of carbon atoms

• it cannot be burnt

The gas evolved on heating alkali formate with soda-lime is

• CO

• CO₂

• hydrogen

• water vapour

The continuous phase contains the dispersed phase throughout, example is

• water in milk

• fat in milk

• water droplets in mist

• oil in water