Questions Related to chemistry

Multiple choice chemistry air and water pollution control smoke, dust and other air pollutants, acid rain air pollutants and its effects air and air pollution

Ammonia is most harmful for:

  1. humans

  2. animals

  3. aquatic organisms

  4. plants

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The toxicity of ammonia solutions does not usually cause problems for humans and other mammals, as a specific mechanism exists to prevent its build-up in the bloodstream. Ammonia is converted to carbamoyl phosphate by the enzyme carbamoyl phosphate synthetase, and then enters the urea cycle to be either incorporated into amino acids or excreted in the urine. Fish and amphibians lack this mechanism, as they can usually eliminate ammonia from their bodies by direct excretion. Hence ammonia even in dilute solutions is very harmful for aquatic organisms.

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

Which of the following statements is false?

  1. Proton has a positive charge

  2. Neutron has no charge

  3. Electrons are found in regions of the atom called orbitals

  4. Electrons has a greater mass than the protons

  5. Protons and neutrons form the nucleons of the atom

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Electron has less mass. A proton and a neutron have effectively the same mass. A proton (or a neutron) has approximately 1837 times more massive than an electron.
Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

$ _{7}{X}^{15}$ and $ _{8}{Y}^{15}$ differ in

  1. Physical properties

  2. Chemical properties

  3. Number of neutrons

  4. Number of nucleons

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The option (C) is the correct answer.
$\displaystyle _{7}{X}^{15}$ and $\displaystyle _{8}{Y}^{15}$ differ in number of neutrons.
Number of neutrons for $\displaystyle _{7}{X}^{15} = 15-7=8$
Number of neutrons for $\displaystyle _{8}{Y}^{15}=15*8=7$
Note: Number of neutrons $\displaystyle =$ mass number $\displaystyle -$ atomic number.

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

Number of neutrons present in $1.7$ g of ammonia is:

  1. $0.8N _A$
  2. $0.7N _A$
  3. $0.652N _A$
  4. $0.52N _A$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Let us consider the problem.
For, moles of $N{H _3} = \frac{{1.7}}{{17}} = 0.1$
Let the Neutrons in 1 molecules of $N{H _3} = 7 + 3 \times 0 = 7$
Hence,
Number of Neurons $= 0.1 \times {N _A} \times 7$
The correct answer is $0.7{N _A}$