<u>Answer:</u> The density of phosphorus is 
<u>Explanation:</u>
To calculate the density of phosphorus, we use the equation:
where,
= density
Z = number of atom in unit cell = 1 (CCP)
M = atomic mass of phosphorus = 31 g/mol
= Avogadro's number = 
a = edge length of unit cell = 
(Conversion factor: 
)
Putting values in above equation, we get:
Hence, the density of phosphorus is
Answer: Options (a) and (d) are the correct answer.
Explanation:
A catalyst is the substance which helps in increasing the rate of reaction.
Activation energy is the minimum amount of energy required by reactants to start the reaction. On addition of catalyst, the path of reaction changes because the energy barrier gap reduces and hence, the activation energy also decreases.
In the absence of catalyst, we need to increase the temperature so that reaction can occur quickly.
Whereas on addition of catalyst, there is no need to increase the temperature as the catalyst itself is sufficient to increase the rate of reaction. As a result, temperature should be lowered when there is addition of catalyst in the reaction.
Thus, we can conclude that catalysts can save money by essentially lowering the activation energy and temperature required.
Answer:
Volume of the concentrated solution, which is needed is 103.30 mL
Explanation:
Let's apply the formula for dilutions to solve the problem
Conc. Molarity . Conc. volume = Dil. Molarity . Dil volume
12.1 M . Conc. volume = 2.5 M . 500 mL
Conc. volume = (2.5 M . 500 mL) / 12.1M
Conc. volume = 103.30 mL
Answer:
Option B. A
Explanation:
From the question given above, the following data were obtained:
C(s) + 2H₂ (g) —> CH₄ (g). ΔH = –74.9 kJ
From the reaction above, we can see that the enthalpy change (ΔH) is negative (i.e –74.9 KJ) which implies that the heat content of the reactants is greater than the heat content of the products. Thus, the reaction is exothermic reaction.
For an exothermic reaction, the energy profile diagram is drawn in such a way that the heat content of reactants is higher than the heat content of products because the enthalpy change
(ΔH) is always negative.
Thus, diagram A (i.e option B) gives the correct answer to the question.
