<span>substances consisting of ions held together by electrostatic attraction
</span>
Answer:Sunlight
Explanation:
Sunlight is a physical factor that really determine the amount of plant life available in an ecosystem. Plants depend on sunlight to produce their own food via photosynthesis. Hence in the absence of sunlight, the amount of plant life will drastically reduce in a given ecosystem. Sunlight is indispensable for plant growth.
Answer: B. trigonal planar
Explanation:
Valence Shell Electron Pair Repulsion Theory (VSEPR) is a model to predict the geometry of the atoms making up a molecule where atoms are arranged such that the forces of repulsion are minimum.
If a central atom is bound to three electron domains ,the number of electron pairs is 3, that means the hybridization will be 
and the electronic geometry of the molecule will be trigonal planar as the electron pairs will repel each other and attain a position which is most stable.
Example: 
with 3 electron domains has trigonal planar geometry.
Answer:
For each scenario as following:
A. 3 Potential deaths by chlorine exposure
B. 1 Potential deaths by chlorine exposure
C. 3 Potential deaths by chlorine exposure
Explanation:
According to Freitag, 1941 Chlorine exposure can be lethal at the concentration of 34-51 ppm in a time of 1h-1.5h. The answers are based on his reference.
We can skip option B and D because NaCl is salt and H₂SO₄ is a strong acid.
Neutralization reactions are those reactions in which acid and base react to form salt and water.
As water being amphoteric in nature can react with HCl as follow,
HCl + H₂O ⇆ H₃O⁺ + OH⁻
In this case no salt is formed, so we can skip this option.
Ammonia being a weak base can abstract proton from HCl as follow,
HCl + NH₃ → NH₄Cl
Ammonium Chloride is a salt. So, among all four options, Option-C is the correct answer.
