Questions with Correct Answers
2025/2026.
Which of the following represents a physical change in matter?
a. a substance changes color when exposed to air
b. a substance produces a gas and a solid when heated
c. a substance burns when heated
d. a substance solidifies at 443 K - Answer d. a substance solidifies at 443 K
Which of the following terms correctly applies to a molecule of CO2?
a. diatomic, heteroatomic
b. polyatomic, diatomic
c. triatomic, homoatomic
d. triatomic, heteroatomic - Answer d. triatomic, heteroatomic
Which of the following is an example of a homogenous mixture?
a. HCl solution
b. soil
c. vinegar and oil salad dressing
d. more than one response is correct - Answer a. HCl solution
Which number has the greatest number of significant digits?
a. 1.0035
b. 17.5000
c. 0.0000625
d. 6.022x10^23 - Answer b. 17.5000
If urine has a density of 1.08 g/mL, what would be the mass of a 125mL urine sample?
a. 135 g
b. 0.00864 g
c. 116 g
d. 125 g - Answer 135 g
, How many electrons are in a neutral atom of carbon-13?
a. 12
b. 18
c. 6
d. no way to tell - Answer c. 6
What is the reason that U-238 is different from U-235?
a. three more electrons
b. three more neutrons
c. three more protons
d. there is no difference - Answer b. three more neutrons
A covalent bond results when
a. one atom gives up an electron to another atom
b. one atom gives up two electrons to another atom
c. two atoms share a pair of electrons
d. two atoms share a single electron - Answer c. two atoms share a pair of electrons
How many hydrogen atoms are in 1.00 mole of NH3?
a. 3.00
b. 6.02 x 10^23
c. 12.0 x 10^23
d. 18.1 x 10^23 - Answer d. 18.1 x 10^23
The total number of f orbitals in an f subshell is _______.
a. 2
b. 5
c. 7
d. 10 - Answer c. 7
How many electrons are in the outer shell of element 15?
a. 5
b. 3
c. 15
d. 2 - Answer a. 5