The ammonia prepared by treating ammonium sulphate with calcium hydroxide is completely used by $$NiCl{}_2.6{H_2}O$$ to form a stable coordination compound. Assume that both the reactions are $$100\% $$ complete. If $$1584$$ $$g$$ of ammonium sulphate and $$952\,g$$ of $$NiC{l_2}.6{H_2}O$$ are used in the preparation, the combined weight (in grams) of gypsum and the nickel-ammonia coordination compound thus produced is _____________.

(Atomic weights in $$g$$ $$mo{l^{ - 1}}:$$ $$H = 1,N = 14,O = 16,$$ $$S = 32,Cl = 35.5,$$ $$Ca = 40,$$ $$Ni = 59$$

The sum of the number of lone pairs of electrons on each central atom in the following species is

$${[TeB{r_6}]^{2 - }},{\left[ {Br{F_2}} \right]^ + },SNF_3,$$ and $${\left[ {Xe{F_3}} \right]^ - }$$

(Atomic numbers: $$N = 7,F = 9,$$ $$S = 16,Br = 35,$$ $$Te = 52,Xe = 54$$)

The possible number of geometrical isomers for the complex [CoL₂Cl₂]^-
(L= H₂NCH₂CH₂O^-) is (are)...