Identify the correct Statements.
1) Alkanes with odd no of carbons have high melting points than alkanes with even No. of carbons.
2) Alkanes with even No. of carbons have higher melting point than next higher and lower alkanes with odd no.of carbon atoms.
3) Grignard reagents react with compounds having acidic hydrogen and give alkanes.
4) The minimum no.of carbons in alkanes required to show optical isomerism is 7.
5) Alkanes and Cyclo alkanes can exhibit geometrical isomerism 
6) Boiling point of alkanes will increase with increase of carbon atoms.