Its a formula relating to specific heat capacity
Δθ refers to the change in temperature
Q refers to the energy neededto raise the temperature of an object by the change in temperature
m stands for the mass of tje object
c is the specific heat capacity which is the amount of energy needed to heat up an object per unit mass
Which of the following measurements is expressed to three significant figures?
C. 5.60 km
Hope this helps!
Actually, no. While their mass may be the same (1kg), the volume of lead is a lot smaller than that of feathers. As there is the same mass stuffed in a smaller space, it must be denser. The density of water is 1 g/cm3, so if the density of the lead is more than 1g/cm3, it has to sink
The correct answer is:
3) Earthquakes can be caused by volcanic eruptions.
You were right :)
Answer: The statement conjugate base of hydrofluoric acid is weaker than that of acetic acid is most likely true.
Explanation:
A strong acid upon dissociation gives a weak conjugate base. This can also be said as stronger is the acid, weaker will be its conjugate base or vice-versa.
Hydrofluoric acid is a strong base as it dissociates completely when dissolved in water.
For example, 
The conjugate base is
which is a weak base.
Acetic acid is a weak acid as it dissociates partially when dissolved in water. So, the conjugate base of acetic acid is a strong base.

Thus, we can conclude that the statement conjugate base of hydrofluoric acid is weaker than that of acetic acid is most likely true.