If then is

The free energy change for the following reactions aregivenbelow-C2H2(g)+O2(g)→2CO2(g)+H2O(l);DG°=–1234KJC(s)+O2(g)→CO2(g);DG°=–394KJ H2(g)+O2(g)→H2O(l);DG°=–237KJWhatisthestandardfreeenergychangeforthe reactionH2(g)+2C(s)→C2H2(g)-

The value of DH–DE for the following reaction at 27°C will be,2NH3(g)→N2(g)+3H2(g)

If at 298K the bond energies of C–H,C–C,C=C and H–H bonds are respectively 414,347,615and 435KJmol–1,thevalueofenthalpy change for there action H2C=CH2(g)+H2(g)→CH3–CH3(g)at298 K will be-

If  then n=

There were two women participating in a chess tournament Every participant played two games with the other participants the number of games that the men played between themselves proved to exceed by 66 the number of games that the men played with the women The number of participants is

153 games were played at a chess tournament with each contestant playing once against each of the others The number of participants is

The number of different ways in which a committee of 4 members formed out of 6 Asians, 3 Europeans and 4 Americans if the committee is to have at least one from each of the 3 regional groups is

A committee of5 is to be formed from 6 boys and 5 girls The number of ways that the committee can be formed so that the committee contains at least one boy and one girl having majority of boys is

If n and  are integers such that  then n c (n‐l, r‐l)=

The least value of the natural number  n satisfying 

 then (n, r)=

 then ‘n’ is

If  = mC₂, then C₂ is equal to -

Students must know how to open expressions like nCr.
Also, the value of n! is n.(n−1).(n−2).....3.2.1.
Combination is used to select r objects from n objects when the arrangement of the objects does not matter.

Twelve students compete for a race. The number of ways in which first three places can be taken, is-