A 4 : 1 molar mixture of He and CH₄ is contained in a vessel at 20 bar pressure. Due to a hole in the vessel the gas mixture leaks out. What is the composition of the mixture effusing out initially?

Complete and balance the following reactions:
Ca₅(PO₄)₃F + H₂SO₄ + H₂O $$\buildrel {Heat} \over \longrightarrow $$ ........ + 5CaSO₄.2H₂O + ........

Statement (S) The alkali metals can form ionic hydrides which contain the hydride ion H^-.
Explanation (E) The alkali metals have low electronegativity; their hydrides conduct electricity when fused and liberate hydrogen at the anode.

The IUPAC name of succinic acid is _______.