Answer:
d). A catalyst lowers the activation energy for a chemical reaction.
Explanation:
From the given choices, it is true that a catalyst lowers the activation energy for a chemical reaction.
The activation energy is the energy barrier that must be overcome before a chemical reaction can occur.
Some reactions have very high activation energy and would not occur without the introduction of a catalyst.
The catalyst brings the reactants into contact by removing the energy deficiency in the system.
Answer:
Diamond
Explanation:
As light moves from a less dense medium to a denser medium it slows down.
This is because the wave length of the light reduces. The denser the medium the less the wavelength. Diamond is the most dense solid among the provided choices thus light travelling through it has the least wavelength.
Answer : The correct option is, (D) 
Explanation : Given,
Concentration of 
= 3 M
Concentration of 
= 1 M
Concentration of 
= 2 M
The given balanced equilibrium reaction is,
The expression for equilibrium constant for this reaction will be,
![K_{eq}=\frac{[NH_3]^2}{[N_2][H_2]^3}](https://tex.z-dn.net/?f=K_%7Beq%7D%3D%5Cfrac%7B%5BNH_3%5D%5E2%7D%7B%5BN_2%5D%5BH_2%5D%5E3%7D)
Now put all the given values in this expression, we get the value of 
Therefore, the value of for the given reaction is, 1.125
45 m. If each student needs 750 mm of tubing, the teacher should order 45 m of tubing.
a) Find the <em>length in millimetres</em>
Length = 60 students x (750 mm tubing/1 student) = 45 000 mm tubing
b) Convert <em>millimetres to metres
</em>
Length = 45 000 mm tubing x (1 m tubing/1000 mm tubing) = 45 m tubing
Answer:
democritus is the first person
