Answer:
sample B contains the larger density
Explanation:
Given;
volume of sample A, V = 300 mL = 0.3 L
Molarity of sample A, C = 1 M
volume of sample B, V = 145 mL = 0.145 L
Molarity of sample B, C = 1.5 M
molecular mass of sodium chloride, Nacl = 23 + 35.5 = 58.5 g/mol
Molarity is given as;

The reacting mass for sample A = 0.3mol x 58.5 g/mol = 17.55 g
The reacting mass for sample B = 0.2175 mol x 58.5 g/mol = 12.72 g
The density of sample A 
The density of sample B 
Therefore, sample B contains the larger density
D. the hyper-dimes
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<u>Answer:</u> The initial concentration of hydrogen peroxide at the given temperature is 0.399 M
<u>Explanation:</u>
Decomposition of hydrogen peroxide is following first order kinetics.
Rate law expression for first order kinetics is given by the equation:
![k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B2.303%7D%7Bt%7D%5Clog%5Cfrac%7B%5BA_o%5D%7D%7B%5BA%5D%7D)
where,
k = rate constant = 
t = time taken for decay process = 855 s
= initial amount of the reactant = ?
[A] = amount left after decay process = 0.321 M
Putting values in above equation, we get:
![2.54\times 10^{-4}s^{-1}=\frac{2.303}{855s}\log \frac{[A_o]}{0.321}](https://tex.z-dn.net/?f=2.54%5Ctimes%2010%5E%7B-4%7Ds%5E%7B-1%7D%3D%5Cfrac%7B2.303%7D%7B855s%7D%5Clog%20%5Cfrac%7B%5BA_o%5D%7D%7B0.321%7D)
![[A_o]=0.399M](https://tex.z-dn.net/?f=%5BA_o%5D%3D0.399M)
Hence, the initial concentration of hydrogen peroxide at the given temperature is 0.399 M
A pure crystalline substance is a substance with an almost perfect regular and periodic pattern in a solid state. This makes this type of substance a hard one compared to an amorphous substance which is soft because of the irregular pattern within.