Using spdf notation, what is the electron configuration for a neutral atom of beryllium

What phase of matter is least common on earth

Plasma is the least common matter on earth

4 0

2 years ago

Thallium-207 decays exponentially with a half life of 4.5 minutes. if the initial amount of the isotope was 28 grams, how many g

Agata [3.3K]

An exponential decay law has the general form: A = Ao * e ^ (-kt) =>

A/Ao = e^(-kt)

Half-life time => A/Ao = 1/2, and t = 4.5 min

=> 1/2 = e^(-k*4.5) => ln(2) = 4.5k => k = ln(2) / 4.5 ≈ 0.154

Now replace the value of k, Ao = 28g and t = 7 min to find how many grams of Thalium-207 will remain:

A = Ao e ^ (-kt) = 28 g * e ^( -0.154 * 7) = 9.5 g

Answer 9.5 g.

7 0

3 years ago

Suppose the half-life is 9.0 s for a first order reaction and the reactant concentration is 0.0741 M 50.7 s after the reaction s

bazaltina [42]

<u>Answer:</u> The time taken by the reaction is 84.5 seconds

<u>Explanation:</u>

The equation used to calculate half life for first order kinetics:

$k=\frac{0.693}{t_{1/2}}$

where,

$t_{1/2}$ = half-life of the reaction = 9.0 s

k = rate constant = ?

Putting values in above equation, we get:

$k=\frac{0.693}{9}=0.077s^{-1}$

Rate law expression for first order kinetics is given by the equation:

$k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}$ ......(1)

where,

k = rate constant = $0.077s^{-1}$

t = time taken for decay process = 50.7 sec

$[A_o]$ = initial amount of the reactant = ?

[A] = amount left after decay process = 0.0741 M

Putting values in equation 1, we get:

$0.077=\frac{2.303}{50.7}\log\frac{[A_o]}{0.0741}$

$[A_o]=3.67M$

Now, calculating the time taken by using equation 1:

$[A]=0.0055M$

$k=0.077s^{-1}$

$[A_o]=3.67M$

Putting values in equation 1, we get:

$0.077=\frac{2.303}{t}\log\frac{3.67}{0.0055}\\\\t=84.5s$

Hence, the time taken by the reaction is 84.5 seconds

6 0

3 years ago

All of the factors described below could account for the difference in the sizes of the tomatoes. Which describes a way in which

disa [49]

Answer:

D my guy

Explanation:

I have a hunch if its biotechnology involved with plants selective breeding seems most appropriate

3 0

3 years ago

A price support is a type of _____. price fixing price floor rent control price ceiling

Oksi-84 [34.3K]

Subsidy

A price support is a type of subsidy. It seems that this is not given in the choices. However, subsidy is a form of monetary or financial support which is provided by a local or state sector. It aims to provide economic and social stability and development. Hence, subsidy encompasses various types of support funded by either government or non-government offices. It can be given in form of either direct (money, incentives and etc.) or indirect (insurance, write-offs and etc.) in procedures.

4 0

3 years ago

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