2 years ago

An electron is in a region outside the nucleus

Chemistry

1 answer:

harkovskaia [24]2 years ago

3 0

Is that a question? Doesnt seem like it

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Can somebody answer this please

Murrr4er [49]

The answer should be A.

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3 years ago

When you dissolve an antacid tablet in water and it produces bubbles, what kind of change is this?

prisoha [69]

Answer: B. a chemical change

Explanation:

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2 years ago

Calculate the number of kilojoules to warm 125 g of iron from 23.5 °C to 78.0 °C.

Pie

3024.75 Joules needed to warm iron

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3 years ago

How many half-lives are required for the concentration of reactant to decrease to 1.56% of its original value?4247.56.56

neonofarm [45]

Answer:

6 half-lives are required for the concentration of reactant to decrease to 1.56% of its original value.

Explanation:

Using integrated rate law for first order kinetics as:

$[A_t]=[A_0]e^{-kt}$

Where,

$[A_t]$ is the concentration at time t

$[A_0]$ is the initial concentration

Given:

Concentration is decreased to 1.56 % which means that 0.0156 of $[A_0]$ is decomposed. So,

$\frac {[A_t]}{[A_0]}$ = 0.0156

Thus,

$\frac {[A_t]}{[A_0]}=e^{-k\times t}$

$0.0156=e^{-k\times t}$

kt = 4.1604

The expression for the half life is:-

Half life = 15.0 hours

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

Where, k is rate constant

So,

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

$\frac{4.1604}{t}=\frac {ln\ 2}{t_{1/2}}$

$t = 6\times t_{1/2}$

<u>6 half-lives are required for the concentration of reactant to decrease to 1.56% of its original value.</u>

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3 years ago

if an object has a mass of 60 grams in a volume of 120 cm3 then calculate the density would this object sink or float

Ivanshal [37]

Answer: 0.5 g/cm^3

Density equals mass divided by volume so..

60/120 is 0.5 g/cm^3

7 0

2 years ago