It is b, i learned this last year hope this helps
VOLUME= 5cm*10cm*2cm =100cm^3
but density of iron=7.874g/cm^3
mass=7.874g*100 =787.4g
mass of that block = 787.4g
The answer is A, Mars and Jupiter.
Ionic compounds generally occur between metals and non-metals due to their large electronegativity difference. You can simple go down Group 1 and Group 17 of the periodic table.
Examples:
NaCl (Sodium Chloride)
KCl (Potassium Chloride)
RbCl (Rubidium Chloride)
CsCl (Cesium Chloride)
THe amount of iron oxide decreases as the level of silica increases.