C. The thermometer reads 100
Answer:
Two half lives.
Explanation:
It is known that the decay of isotopes and radioactive material obeys first order kinetics.
Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
That means for a sample 100% to decay to 50 % it will take one half-life, and to decay the remaining 50% to 25% it will take another half-life.
So, for a sample has 25% parent and 75% daughter it will have two half-lives.
Answer is: <span>the empirical formula of the hydrocarbon is CH</span>₂.<span>
Chemical reaction: C</span>ₓHₐ + O₂ → xC + a/2H₂O.<span>
m(CO</span>₂) = 33.01 g.
n(CO₂) = m(CO₂) ÷ M(CO₂).
n(CO₂) = 33.01 g ÷ 44.01 g/mol.
n(CO₂) = n(C) = 0.75 mol.
m(H₂O) = 13.52 g.
n(H₂O) = 13.52 g ÷ 18 g/mol.
n(H₂O) = 0.75 mol.
n(H) = 2 · n(H₂O) = 1.5 mol.
n(C) : n(H) = 0.75 mol : 1.5 mol /0.75 mol.
n(C) : n(H) = 1 : 2.
Answer: The final temperature is 
Explanation:

As we know that,

.................(1)
where,
q = heat absorbed or released
= mass of lead = 50 g
= mass of water = 75 g
= final temperature = ?
= temperature of lead = 
= temperature of water = 
= specific heat of lead = 
= specific heat of water= 
Now put all the given values in equation (1), we get
![50\times 0.11\times (T_{final}-373)=-[75\times 1.0\times (T_{final}-273)]](https://tex.z-dn.net/?f=50%5Ctimes%200.11%5Ctimes%20%28T_%7Bfinal%7D-373%29%3D-%5B75%5Ctimes%201.0%5Ctimes%20%28T_%7Bfinal%7D-273%29%5D)

Therefore, the final temperature of the mixture will be 279.8 K.