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Karo-lina-s [1.5K]
4 years ago
9

Do H, K, Rb, Fr, have the same number of valence electrons or same number of energy levels

Chemistry
1 answer:
julsineya [31]4 years ago
5 0

Answer:

Same number of valance electrons

Explanation:

All of them are in group 1 so they have 1 valance electron.

If they were in same period they would have same number of energy levels.

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The heat exchange in chemical reactions is due to a change in:
Paha777 [63]

Answer:

B

Explanation:

This would be due to enthalpy. This is because that this where heat exchange happens in chemical reactions.

So, a positive enthalpy means that the reaction is endothermic (heat entering) and if enthalpy is negative this will be a exothermic (heat released)

Another example would be the use of atoms. This example if temperature is the factor, this means that at low temp there is less kinetic energy so low temperature. However, an increase in energy means that there is more kinetic energy in the atoms which means that more collisions occurring.

Hope this helps !!!!

Have a nice day :)

5 0
4 years ago
A sample contains 25% parent isotope and 75% daughter isotopes. If the half-life of the parent isotope is 72 years, how old is t
alisha [4.7K]

The radioactive decay obeys first order kinetics

the rate law expression for radioactive decay is

ln\frac{[A_{0}]}{[A_{t}]}=kt

Where

A0 = initial concentration

At = concentration after time "t"

t = time

k = rate constant

For first order reaction the relation between rate constant and half life is:

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

Let us calculate k

k = 0.693 / 72 = 0.009625 years⁻¹

Given

At = 0.25 A0

ln(\frac{A0}{0.25A0})=0.009625  X time

time = 144 years

So after 144 years the sample contains 25% parent isotope and 75% daughter isotopes**

Simply two half lives

5 0
3 years ago
Read 2 more answers
Please answer this question​
vova2212 [387]

Answer:

Yes

Explanation:

Natural gas is colorless and odorless, and explosive, so a sulfur-smell (similar to rotten eggs) is usually added for early detection of leaks. ... Natural gas is a fossil fuel. Natural gas is a non-renewable hydrocarbon used as a source of energy for heating, cooking, and electricity generation.

5 0
3 years ago
Select all of the answers that apply.
shtirl [24]
The odysseyware answer is the same as his wood manure and food crops
5 0
4 years ago
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Whats the name of S4O6
IceJOKER [234]

Answer:

Sulfonic acid

Explanation:

I think this is correct

8 0
3 years ago
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