Ans: Elements in the same period have the same number of electron shells.
Answer:
A.It lowers the melting point of alumina. B.It increases the electrical conductivity. ... Hint: The solution of alumina and cryolite during the electrolysis gives the aluminium at cathode and oxygen at anode. The alumina is a poor conductor of electricity and the fusion temperature of alumina is about 2000∘C.
90 chemical elements have two letters in their symbols.

now split the equation in half
CH4+O2 I CO2 + 4H2O
C = 1 I C = 1
H = 4 I H = 8
O = 2 I O = 3
CH4+ 2O2 = CO2 + 2H20