Better method for preparation of \( \mathrm{BeF}_2 \), among the following is :
The oxide that gives \( \mathrm{H_2O_2} \) most readily on treatment with \( \mathrm{H_2O} \) is:
One of the by-products formed during the recovery of \( \mathrm{NH_3} \) from Solvay process is :
