Answer:
Conditions for geometrical isomerism: There are two necessary conditions for a compound to possess geometrical isomerism:
(i) It must contain a carbon-carbon double bond in the molecule.
(ii) Two unlike atoms or groups must be linked to each doubly bonded carbon atoms
Answer:
There is one single covalent bond between two carbon atoms.
Explanation:
We know that sharing of electrons form covalent bonds.
If we look upon K,L,M ,N shells of the carbon and hydrogen atoms.
We found that Hydrogen is having only 
electron in K shell.
And Carbon on the other hand is having 
electrons in K shell and 
electrons in L shell.
So carbon have valence electrons,and it can share bonds with any relevant atom to complete its octet.
And Hydrogen requires electron to complete its doublet.
Alkane general formula 
For ethane 
Carbon atom is shared by 
Hydrogen.
The remaining one electron 
of carbon will be shared with another carbon atom.
An image of the sharing of electrons attached below,
Hence we have only covalent bond between the two.
Calcium carbonate will be formed which is insoluble in water.
The answer is a) K and CrO4 only.
Convert mole to gram by multiplying the molar mass of sodium
0.500mol Na x 22.990g = 11.495g of Na
