Identify each of the following as a six-carbon or a three-carbon compound and arrange them in the order in which they occur in glycolysis:

b. pyruvate

What are the important processes in the water cycle?

The mass number of carbon.

Carbon-14 is a radioactive element with a half-life of about 5,730 years. Carbon-14 is said to decay exponentially. The decay rate is $0.000121$. We start with one gram of carbon- 14. We are interested in the time (years) it takes to decay carbon-14.

Find the amount (percent of one gram) of carbon-14 lasting less than 5,730 years. This means, find $P(x<5,730)$.

Find the probability. $P(x<5,730)=$ $\rule{1cm}{1pt}$.

GENERAL: Carbon-14 Dating The proportion of carbon-14 still present in a sample after t years is $e^{-0.00012 t}$. Estimate the age of the cave paintings discovered in the Ardéche region of France if the carbon with which they were drawn contains only 2.3% of its original carbon- 14 . They are the oldest known paintings in the world.

When people smoke, carbon monoxide is released into the air. In a room of volume $60 \mathrm{~m}^3$, air containing $5 \%$ carbon monaxide is introduced at a rate of $0.002 \mathrm{~m}^3 / \mathrm{min}$. (This means that $5 \%$ of the volume of the incoming air is carbon monaxide.) The carbon moncxide mixes immediately with the rest of the air, and the mixture leaves the room at the same rate as it enters.

(b) Solve the differential equation, assuming there is no carbon monca ide in the room initially.

Carbon-carbon bond dissociation enthalpies have been measured for many alkanes. Without referring to Table $4.3$, identify the alkane in each of the following pairs that has the lower carbon-carbon bond dissociation enthalpy, and explain the reason for your choice.

(a) Ethane or propane

(b) Propane or 2-methylpropane

(c) 2-Methylpropane or 2,2-dimethylpropane

Draw the orbital diagram for carbon in $\mathrm{CO}_2$ showing how many carbon atom electrons are in each orbital.

Explain the role of the Calvin cycle in photosynthesis.

Which of the following gases is produced in the atmosphere as a result of photosynthesis?

(a) carbon dioxide

(b) oxygen

(c) nitrogen

(d) carbon monoxide

The atomic number for carbon is six. How many neutrons are in carbon-$13$ ? A. $6$ B. $7$ C. $12$ D. $13$

The half-life of carbon- 14 is 5715 years. How long will it be until only half of the carbon- 14 in a sample remains?

Explain the importance of RuBisCo in the Calvin cycle:

Explain how a convection cycle is generated.