1. Answer;
- Exothermic reaction
Explanation;
-Exothermic reactions are types of chemical reactions in which heat energy is released to the surroundings. Since enthalpy change is the difference between the energy of products an that of reactants. It means that in an exothermic reaction the energy of products is less than that of products. In this case an energy of 315kJ is released to the surroundings.
2. Answer;
Conserved
-The total amount of energy before and after a chemical reaction is the same. Thus, energy is conserved.
Explanation;
-According to the law of conservation of energy, energy is neither created nor destroyed. Energy may change form during a chemical reaction. For example, energy may change form from chemical energy to heat energy when gas burns in a furnace. However, the exact amount of energy remains after the reaction as before, which is true for all chemical reactions.
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Answer:</h3>
5.71 × 10² nm
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Explanation:</h3>
The product of wavelength and frequency of a wave gives the speed of the wave.
Therefore;
Velocity of wave = Wavelength × Frequency
c = f ×λ
In our case;
Frequency = 5.25 × 10^14 Hz
Speed of light = 2.998 × 10^8m/s
But;
λ = c ÷ f
= 2.998 × 10^8m/s ÷ 5.25 × 10^14 Hz
= 5.71 × 10^-7 m
But; 1 M = 10^9 nm
Therefore;
wavelength = 5.71 × 10^-7 × 10^9
= 5.71 × 10² nm
The wavelength of light wave 5.71 × 10² nm
Answer: At the point when space experts take a gander at an article's range, they can decide its arrangement dependent on these frequencies. The most well-known technique stargazers use to decide the sythesis of stars, planets, and different articles is spectroscopy. This spread-out light is known as a range.
Explanation:
Answer: 20 gallons of 16% and 8 gallons of 23% solution is usedfor 28 gallons of the 18 % solution.
Explanation:
According to the dilution law,
where,
= concentration of ist disinfectant solution = 16 %
= volume of pure acid solution = x gallons
= concentration of another disinfectant solution= 23%
= volume of another acid solution= (28-x) gallons
= concentration of resulting disinfectant solution = 18 %
= volume of resulting acid solution = 28 gallons

(28-x) = (28-20) = 8 gallons
Thus 20 gallons of 16% and 8 gallons of 23% solution is usedfor 28 gallons of the 18 % solution.