Q1. What is the mass number of an iron atom that has 28 neutrons?

Q2. Calculate the number of neutrons of 239Pu.

Q3. Write the appropriate symbol for each of the following isotopes: (a) Z= 11, A= 23; (b) Z= 28, A= 64

Q4. Define, with two examples, the following terms: (a) alkali metals, (b) alkaline earth metal, (c) halogens, and (d) noble gases.

Q5. Identify the following as elements or compounds: (a) NH3, (b) N2, (c) CO, (d) Co, and (e) He.

Q6. Give the numbers of protons and electrons in each of the following: (a) Na+, (b) Ca2+, (c) Al3+, (d) I, (e) O2, (f) N3, and (g) He.

Q7. Write the molecular formula of glycine, an amino acid present in proteins.

Carbon = 2 atoms
Hydrogen = 5 atoms
Nitrogen = 1 atom
Oxygen = 2 atoms.

Q8. Which of the following compounds are likely to be ionic? Which are likely to be molecular? (a) SiCl₄, (b) LiF, (c) BaCl₂, (d) B₂H₆, (e) KCl, and (f) C₂H₄

Q9. What is the difference between inorganic compounds and organic compounds?

Q10. Name the following compounds.

• Na₂CrO₄
• K₂HPO₄
• HBr (gas)
• HBr (in water
• Li₂CO₃
• K₂Cr₂O₇
• FeO
• PF₃
• NH₄NO₂
• Al(OH)₃
• TiCl₄
• CuSO₄ 5H₂O

Q11. Write the formulas for the following compounds:

• rubidium nitrite
• potassium sulfide
• calcium hydrogen phosphate
• iodine heptafluoride
• ammonium sulfate
• copper (II) nitrite
• calcium hydroxide
• dihydrogen sulfide
• sodium hydride

Q12. The following table gives the number of electrons, protons, and neutrons in atoms or ions of four elements, identified only as A, B, C, and D. Write the isotopic symbol for each element.