Question
An isotope of chromium is represented by \(_{24}^{52}\textrm{Cr}\). Which statement about an atom of this isotope of chromium is correct?
A. It contains 24 electrons.
B. It contains 24 neutrons.
C. It contains 28 protons.
D. It contains 52 neutrons.
▶️Answer/Explanation
Ans:
A
Isotopes have same atomic number i.e. same number of protons and electrons. Its isotope will also have 24 number of electrons.
Question
Which statement explains why graphite is used as a lubricant?
A All bonds between the atoms are weak.
B It conducts electricity.
C It has a low melting point.
D Layers in the structure can slide over each other.
▶️Answer/Explanation
Ans:D
Layers in the structure can slide over each other hence it is used as a lubricant.
Question
Which definition of isotopes is correct?
A atoms of the same element that have the same number of electrons and nucleons
B atoms of the same element that have the same number of neutrons and protons
C atoms of the same element that have the same number of protons but a different number of
electrons
D atoms of the same element that have the same number of protons but a different number of
nucleons
▶️Answer/Explanation
Ans: D
Isotopes are atoms of the same element that have the same number of protons but a different number of nucleons.
Question
Two isotopes of carbon are \(^{12}C\) and \(^{14}C\).
Which statement about these two isotopes is correct?
A Their electronic structure is different.
B They have different numbers of nucleons.
C They have different numbers of protons.
D They have the same number of neutrons.
▶️Answer/Explanation
Ans: B
They have same number of protons =6.
C-12 has 12-6=6 neutrons. C-14 has 14-6=8 neutrons.
They have different number of neutrons.
Question
Which row describes the structure and a use of diamond?
▶️Answer/Explanation
Ans: C
Structure of diamond in giant molecular structure which is macromolecular.
It is one of the hardest materials. Hence it is used in cutting tools.