The mass percent of element X in X(NO3)2 is 52.55%.
Chemical analysis of a pure
sample of X(NO3)2 shows that
it contains 67.50 g of element
X. What is the total mass of
the pure sample?

128.4 g

Explanation:

Step 1: Given data

Step 2: Determine the total mass of the sample

The mass percent of element X in X(NO₃)₂ is 52.55%, that is, there are 52.55 g of X every 100 g of X(NO₃)₂. Then, the mass of X(NO₃)₂ that contains 67.50 g of X is:

67.50 g X × 100 g X(NO₃)₂/52.55 g X = 128.4 g X(NO₃)₂

"the periodic table is arranged in order of atomic number."