What’s the general form of double replacement reaction?

Which of the following pairs of elements belong to the same groupa. h and he b. li and bec. c and pb d. ga and ge

Ican determine the molar mass of an element by looking on the under the atomic mass for the element. for example the molar mass of phosphorus is 30.974 grams/mole. avogadro’s number tells me the amount of representative particles in 1 mole of any substance. this means 12.011 gram sample of carbon and a 32.0 gram sample of sulfur have the same number of atoms.

What is the formula of the ionic compound composed of calcium cations and chloride anions