Answer: The rate constant is
Explanation ;
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = ?
t = age of sample = 4.26 min
a = initial amount of the reactant = 2.56 mg
a - x = amount left after decay process = 2.50 mg
Now put all the given values in above equation to calculate the rate constant ,we get



Thus rate constant is [tex]0.334s^{-1}
Answer:

Explanation:
Hello there!
In this case, according to the given chemical reaction:
2 Al + 3 Cl2 --> 2 AlCl3
Whereas there is a 2:3 mole ratio of aluminum to chlorine; it will be possible for us to calculate the required grams of aluminum by using the equality 22.4 L = 1 mol, the aforementioned mole ratio and the atomic mass of aluminum (27.0 g/mol) to obtain:

Regards!
Answer:

Explanation:
Hello,
In this case, we can consider that the given heat of combustion is indeed the heat of reaction since it corresponds to the combustion of propane, which is computed by using the heat formation of all the involved species as shown below:

Thus, since the heat of formation of gaseous carbon dioxide is -393.5 kJ/mol, water -241.8 kJ/mol and oxygen 0 kJ/mol, the heat of formation of propane is:

Best regards.
Answer:
B.
Explanation:
The telescopes of the 1600s were gradually improved upon over time, resulting in the telescopes that are available today.
Atoms<span> are </span>arranged in molecular compounds in groups.
<span>
For </span>covalent compounds<span>: </span>
<span>consider drawing the lewis structure of the covalent compound in question, putting the atom which is least electronegative (save hydrogen) in the center.
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