Question

1- How many moles of N2O5 contain the same number of nitrogen atoms as exactly 19 mol of NO2?

2- How many grams are contained in 0.900 mol of calcium phosphate, Ca3 (PO4)2?

3- Ga

Number of electrons =_______ electrons

Number of protons = _________protons

4- element number 79

Number of electrons = _____electrons

Number of protons = ______protons

5- What are the symbol and name for an element whose average atoms have a mass that is 59.6% of the mass of an average chromium atom?

Symbol:

Name:

6- In the first 36 elements, 8 elements have atoms whose average mass is within 0.2 u of being twice the atomic number of the element. Choose the symbols and names for these 8 elements.

(Select all that apply.)

- oxygen

-silicon

-chlorine

-helium

-bromine

-sulfur

-boron

-argon

-aluminum

-carbon

-lithium

-calcium

-nitrogen

-neon

-copper

-sodium