Unit 1: Fundamentals of Chemistry

31. Which of the following is an example of a physical change?

A) Rusting of iron
B) Burning of wood
C) Melting of ice
D) Digestion of food
Answer: C) Melting of ice

32. What is the main component of acid rain?

A) Nitric Acid
B) Hydrochloric Acid
C) Sulfuric Acid
D) Acetic Acid
Answer: C) Sulfuric Acid

33. Which element is a liquid at room temperature?

A) Chlorine
B) Mercury
C) Lead
D) Sodium
Answer: B) Mercury

34. Which gas is used in fire extinguishers?

A) Oxygen
B) Carbon Dioxide
C) Nitrogen
D) Helium
Answer: B) Carbon Dioxide

35. Which of the following is an allotrope of carbon?

A) Graphite
B) Quartz
C) Diamond
D) Both A and C
Answer: D) Both A and C

36. Which acid is found in the stomach?

A) Hydrochloric Acid
B) Sulfuric Acid
C) Nitric Acid
D) Acetic Acid
Answer: A) Hydrochloric Acid

37. Which of the following compounds is ionic?

A) CO2
B) H2O
C) NaCl
D) CH4
Answer: C) NaCl

38. What is the chemical formula for calcium carbonate?

A) CaO
B) CaCl2
C) CaCO3
D) CaSO4
Answer: C) CaCO3

39. What is the charge on a sulfate ion (SO4)?

A) +1
B) -1
C) -2
D) +2
Answer: C) -2

40. Which of the following metals is most reactive?

A) Gold
B) Silver
C) Potassium
D) Copper
Answer: C) Potassium