For which of the following activities might you want to hire a chemist?
Answer: D. testing a rock sample for gold content
Which of the following procedures involves a physical change in one of the substances?
Answer: C. separating a salt solution by evaporating the water
A graph depicting a direct relation is a straight line and usually has positive slope. An inverse relation is a curve, typically concave up with negative slope.
[H+] in first brand:
4.5 = -log([H+])
[H+] = 10^(-4.5)
[H+] in second brand:
5 = -log[H+]
[H+] = 10^(-5)
Difference = 10^(-4.5) - 10^(-5)
= 2.2 x 10⁻⁵
The answer is A.
Explanation: Walking for 30 minutes covers a distance of 2.0 to 2.5 km and burns about 125 calories
Answer: c. ΔH˚ is positive and ΔS˚ is positive
Explanation:
According to Gibb's equation:
= Gibbs free energy
= enthalpy change
= entropy change
T = temperature in Kelvin
= +ve, reaction is non spontaneous
= -ve, reaction is spontaneous
= 0, reaction is in equilibrium
Thus for 
Case :
>
when 
both have positive values.
Reaction is spontaneous only at at high temperatures.
