Question

1. in a controlled experiment, which variable is deliberately changed?

a) dependent variable
b) control variable
c) independent variable
d) experimental error

1. which subatomic particle has a positive charge?

a) neutron
b) electron
c) isotope
d) proton

1. which of the following is the atomic number of an element?

a) the total number of protons and neutrons
b) the number of neutrons
c) the number of protons
d) the number of electrons

1. what is the atomic mass number of an atom with 6 protons and 6 neutrons?

a) 18
b) 3
c) 6
d) 12

Explanation:

• For question 3: In a controlled experiment, the independent variable is the one that is deliberately manipulated or changed to observe its effect on the dependent variable. Control variables are kept constant. Experimental error is an unwanted deviation.
• For question 4: Protons have a positive charge, neutrons are neutral, electrons have a negative charge, and isotopes are different forms of an element with the same number of protons but different numbers of neutrons.
• For question 5: The atomic number of an element is defined as the number of protons in the nucleus of an atom of that element.
• For question 6: The atomic mass number is the sum of the number of protons and neutrons in an atom. So for an atom with 6 protons and 6 neutrons, 6 + 6 = 12.

Answer:

1. c) Independent variable
2. d) Proton
3. c) The number of protons
4. d) 12