Answer:
3.02× 10²⁴ atoms
Explanation:
Given data:
Number of nitrogen atoms = ?
Number of moles of N₂O = 2.51 mol
Solution:
1 mole contain 2 mole of nitrogen atoms.
2.51 × 2 = 5.02 mol
According to Avogadro number,
1 mole = 6.022 × 10²³ atoms
5.02 mol × 6.022 × 10²³ atoms / 1 mol
30.2 × 10²³ atoms
3.02× 10²⁴ atoms
Answer:- 
Explanations:- The first reaction is combustion reaction as the hydrocarbon is burned in presence of oxygen to give carbon dioxide and water.
Second reaction is the synthesis reaction as in general a synthesis reaction looks like:

Third reaction is the decomposition reaction as it looks opposite of synthesis reaction.

In general, a single displacement reaction looks like:

Fourth reaction is single replacement reaction as bromine is replaced by chlorine.
So, the correct choice is the last reaction,
.
Answer:
hope it helps.
Explanation:
Zinc metal dissolves slowly in dilute sulphuric acid to form solutions containing the aquated Zn(II) ion together with hydrogen gas, H2.
Water is an essential part of life and its availability is important for all living creatures. On the other side, the world is suffering from a major problem of drinking water. There are several gases, microorganisms and other toxins (chemicals and heavy metals) added into water during rain, flowing water, etc. which is responsible for water pollution. This review article describes various applications of nanomaterial in removing different types of impurities from polluted water. There are various kinds of nanomaterials, which carried huge potential to treat polluted water (containing metal toxin substance, different organic and inorganic impurities) very effectively due to their unique properties like greater surface area, able to work at low concentration, etc. The nanostructured catalytic membranes, nanosorbents and nanophotocatalyst based approaches to remove pollutants from wastewater are eco-friendly and efficient, but they require more energy, more investment in order to purify the wastewater. There are many challenges and issues of wastewater treatment. Some precautions are also required to keep away from ecological and health issues. New modern equipment for wastewater treatment should be flexible, low cost and efficient for the commercialization purpose.