Hello!
To find the number of atoms in 2.822 moles of nickel, we need to multiply it by Avogadro's number. Avogadro's number is 6.02 x 10^23 atoms.
2.822 moles x (6.02 x 10^23) ≈ 1.698844 x 10^24
Therefore, there are about 1.70 x 10^24 atoms (according to the number of significant figures) in 2.822 moles of nickel.
Answer: The frequency of the wave is 0.5 hertz.
Explanation:

= Frequency of the wave
= speed of the light in m/s
= Wavelength of the wave.
Here in question we are given with speed of the infrared light. So, we will replace the value of speed of light(c) from the given value of the speed of the infrared light.
Speed of infrared light = 6 m/s

The frequency of the wave is 0.5 hertz.
Answer:
Keep temperature constant and increase the pressure of the reaction. The rate of reaction increases.
Explanation:
First of all, the question is asking us to design an experiment to investigate the effect of pressure on the rate of reaction hence the pressure can not be held constant since it is the variable under investigation. This eliminates the first option.
Secondly, increasing the pressure of the reaction means that particles of the gas collide more frequently leading to a greater number of effective collisions and a consequent increase in the rate of reaction according to the collision theory.
Hence the answer above.