Give two uses of beryllium and magnesium.

(N/A) Beryllium is used in the manufacture of alloys,particularly copper-beryllium alloys,which are used in the preparation of high-strength springs. It is also used in making windows for $X$-ray tubes.
Magnesium is used in flash powders and bulbs,incendiary bombs,and signals. $A$ suspension of magnesium hydroxide,$Mg(OH)_2$,in water (known as milk of magnesia) is used as an antacid in medicine.