ANSWER KEY ,CHEMISRTY ,std 10 1

2. 3.

a) 1s2 2s2 2p6 3s23p63d5 (1) b)Fecl3 (1) c) In the case of transition elements , diff in energy between outermost s sub shell and penultimate d sub shell is very small.Hence electrons in d sub shell also take part in chemical reaction. (2) oxygen ,5 mole (2) a)Surface area increases,no of molecules undergoing effective collision increases .Hence reaction rate increases. (2) b)Firewood is cut in to small pieces (1)

4. a) b,d

(2)

5.

a)6.022*10^23

b) 6.022*10^23

c) 32 g

6.

a)Pale yellow precipitate is formed slowly (1)

d) 3*6.022*10^23

(4*1/2=2)

b)As temp increases, the no of molecules with threshold energy increases,as a result the no of effective collision increases and the rate of reaction increases (2) 7. a) B,D (1) b)C,D (1) c) C (1) d)A (1) 8. 9.

when pressure increases,the molecules come closer,the no of molecules per unit volume increases,no of collision increases and reaction rate increases. (3) A) No of atoms in SO2= (100/64)*3*6.022*10^23 No of atoms in NaOH=(100/40)*3*6.022*10^23 (4) NaOH have greater no of atoms. B) a)64g (2) b)no. Of moles=112/22.4=5 moles no of GMM in 112 lit of NH3=5 (2)

10. 11. 12. 13. 14.

1s2 2s2 2p6 3s2 3p6 3d10 4s1 Because the completely filled d sub shell show greater stability (2) a) N2+3H2- 2NH3 forward (1) 2NH3- N2+3H2 backward (1) b) when rate of forward reaction= rate of backward reaction (1) a) 6.022*10^23 molecules (1) b)2 mole (1) a) Q (1) b) T (1) c)S (1) a) 58.5 g , take 58.5g NaCl and dissolve in water and make the volume of the solution one litre (2) b)Make the volume of the solution 2 litre by adding more water (1) Prepared by Noushad and Ranjini ,GHSS Mangalpady Kasragod.