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IrinaVladis [17]
3 years ago
13

Which radioactive isotope would take the least amount of time to become stable? rubidium-91 iodine-131 cesium-135 uranium-238

Chemistry
2 answers:
Masteriza [31]3 years ago
5 0
The answer is rubidium -91 because it takes a shorter time of 58.4 seconds to become stable.
DanielleElmas [232]3 years ago
5 0

Answer:

the answer is A

Explanation:

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How many bonds are present in Cl20?<br> a. 2<br> b. 4<br> c. 1<br> d. 3
steposvetlana [31]

Answer:

A. 2 bonds

Explanation:

If you see a charch of ci20 it would easily show the answer.

8 0
3 years ago
Which of these half-reactions represents reduction?
gogolik [260]

Answer: The half-reactions represents reduction are as follows.

  • Cr_{2}O^{2-}_{7} \rightarrow Cr^{3+}
  • MnO^{-}_{4} \rightarrow Mn^{2+}

Explanation:

A half-reaction where addition of electrons take place or a reaction where decrease in oxidation state of an element  takes place is called reduction-half reaction.

For example, the oxidation state of Cr in Cr_{2}O^{2-}_{7} is +6 which is getting converted into +3, that is, decrease in oxidation state is taking place as follows.

Cr_{2}O^{2-}_{7} + 3 e^{-} \rightarrow Cr^{3+}

Similarly, oxidation state of Mn in MnO^{-}_{4} is +7 which is getting converted into +2, that is, decrease in oxidation state is taking place as follows.

MnO^{2-}_{4} + 5 e^{-} \rightarrow Mn^{2+}

Thus, we can conclude that half-reactions represents reduction are as follows.

  • Cr_{2}O^{2-}_{7} \rightarrow Cr^{3+}
  • MnO^{-}_{4} \rightarrow Mn^{2+}
3 0
3 years ago
Mass does not change during a chemical change. is the same true for physical change?
Mashutka [201]

Answer:

Mass states that mass is neither created nor destroyed in a chemical reaction or a physical transformation

Explanation:

4 0
3 years ago
A substance X contains 10 gram of calcium carbonate calculate the number of mole of calcium carbonate present in X ​
Tasya [4]

\LARGE{ \boxed{  \rm{ \red{Required \: answer}}}}

☃️ Chemical formulae ➝ \sf{CaCO_3}

<h3><u>How to find?</u></h3>

For solving this question, We need to know how to find moles of solution or any substance if a certain weight is given.

\boxed{ \sf{No. \: of \: moles =  \frac{given \: weight}{molecular \: weight} }}

<h3><u>Solution:</u></h3>

Atomic weight of elements:

Ca = 40

C = 12

O = 16

❍ Molecular weight of \sf{CaCO_3}

= 40 + 12 + 3 × 16

= 52 + 48

= 100 g/mol

❍ Given weight: 10 g

Then, no. of moles,

⇛ No. of moles = 10 g / 100 g mol‐¹

⇛ No. of moles = 0.1 moles

☄ No. of moles of Calcium carbonate in that substance = <u>0.1 moles</u>

<u>━━━━━━━━━━━━━━━━━━━━</u>

3 0
3 years ago
Read 2 more answers
An X-ray beam with λ = 157 pm incident on the surface of a crystal produced a maximum reflection at an angle of θ = 28.5 ∘. Assu
WARRIOR [948]

Answer:

The separation between layers of atoms in the crystal is 164.52 pm.

Explanation:

Formula used

n \lambda = 2d\sin \theta (Bragg's law)

Where :

n = an order of reflection (integer)

\lambda = wavelength of the beam incident X-ray

d = spacing between the layer

θ = incident angle ( angle between ray and scatter plane)

We have :

λ = 157 pm

θ = 28.5°

n = 1

d = ?

1\times 157 pm= 2d\sin (28.5^o) (Bragg's law)

d=\frac{1\times 157 pm}{2\times \sin (28.5^o)}=164.52 pm

The separation between layers of atoms in the crystal is 164.52 pm.

8 0
3 years ago
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