I think the correct answer is D
Atomic Numbers are the number of protons within the nucleus,
which is 58 here.
Atomic Number=58
Mass Number is the sum of the protons and neutrons in the nucleus,
=58+82
Mass Number=140
Periodic symbol of this isotope is entirely dependent on the number of protons, 58, which corresponds to the element Cerium, abbreviated as Ce in the periodic table.
Periodic Symbol=Ce
Answer:
0.011 moles
Explanation:
There are about 6.02*10^23 atoms in a mole, so in the given sample, there are

which is about 0.011 moles.
Answer:
313, 6grams of H3PO4
Explanation:
We calculate the weight of 1 mol of H3PO4:
Weight 1 mol H3PO4= (Weight H)x3+ (Weight P)+(Weight 0)x4 =1gx3+31g+16gx4
Weight 1 mol H3PO4=98 g /mol
1 mol-----98 grams H3PO4
3,2mol----x= (3,2molx 98 grams H3PO4)/ 1mol=313,6 grams H3PO4