true.the babies havn't been born and are inside a fragile egg,so the mother has to protect the eggs.
<span>the change in entropy is positive and change in enthalpy is negative.and potential energy is lower.and the reason is materials in nature naturaly want to get stabler and more chaotic.
for the second question there is a big formula.Equilibrium θ=mcθ1(water)+mcθ1(metal) /mc(water)+mc(metal) just put numbers and it is easy to solve.equlibrium temperture is 23.5</span>
Acid rain is a form of chemical weathering that wears away marble buildings.
Global warming and climate change can cause habitats to no longer suit animals needs and not all animals can easily adapt. Climate change can kill if severe enough
Answer : The time required for decay is, 84 days.
Explanation :
Half-life of chromium-51 = 28 days
First we have to calculate the rate constant, we use the formula :



Now we have to calculate the time required for decay.
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = time taken by sample = ?
a = let initial activity of the sample = 100
a - x = amount left after decay process = 12.5
Now put all the given values in above equation, we get


Therefore, the time required for decay is, 84 days.