Multiple choicea sample of a pure ionic compound has a mass of 2.00 g. if 0.72 g of the sample is determined to be made up of calcium, what is the formula of the compound? a. cao b. caf2 c. cas d. cacl2 e. case f. cabr2

What we can actually do is to find the number of moles of Ca.

moles Ca = 0.72 g / (40.08 g/mol) = 0.018 mol

From the given choices, we can all see that there are 1 mol of compound per 1 mole of Ca. Therefore the actual moles of compound is also 0.018 mol. From this, calculate the mass and the answer is the one which will give 2 g.

D. CaCl2

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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