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3 years ago

How much of a sample of radio-isotope remais after one half life?

Chemistry

1 answer:

Tatiana [17]3 years ago

3 0

Half-life is defined as the time which is taken to reduce the initial amount of isotopes by half.

Hence, after one half-life, half of initial amount of isotopes will remain.

The equation for the half-life, t1/2 = ln 2 / λ, where λ is the decay constant.

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#2: A gas at unknown pressure and a volume of 66 cm has its pressure changed to 150 kPa. The new volume

Murljashka [212]

Answer:

Explanation:

The original pressure can be found by using the formula for Boyle's law which is

$P_1V_1 = P_2V_2$

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume

Since we're finding the original pressure

$P_1 = \frac{P_2V_2}{V_1} \\$

150 kPa = 150,000 Pa

We have

$P_1 = \frac{150000 \times 166}{66} = \frac{24900000}{66} \\ = 377272.72...$

We have the final answer as

Hope this helps you

7 0

3 years ago

The energy needed to remove an electron from an atom is called

Arlecino [84]

Ionization energy, also called ionization potential, in chemistry, the amount of energy required to remove an electron from an isolated atom or molecule

3 0

3 years ago

5. Which quantities must be conserved in all chemical reactions?

sergey [27]

A force of attraction that holds atom together
When atoms react they form a chemical bond which is defined as a force of attraction that holds atom together. A force of attraction is defined as a kind of force that draws two or more objects together regardless of distance. There are two major categories of forces of attraction, one is intramolecular and intermolecular. Intramolecular forces is the presence of forces in atoms internally. While intermolecular is the force by which the force that is existent in two or more elements.

3 0

3 years ago

Read 2 more answers

9. In a period, do the number of shielding electrons change? Why do you think

Setler79 [48]

Answer:

The nuclear charge increases, but the number of inner shielding electrons stays the same.

Explanation:

Their shielding does not change, so the effective nuclear charge — the charge felt by a valence electron — increases.

The valence electrons are pulled closer to the nucleus, decreasing the atomic radius.

For example, consider the elements of Period 3.

$\begin{array}{ccccc}& & \textbf{Number of} & \textbf{Inner} & \textbf{Valence}\\\textbf{At. No.} & \textbf{Symbol} & \textbf{Protons} & \textbf{Electrons} & \textbf{Electrons}\\11& \text{Na} & 11 & 10 & 1\\12& \text{Mg} &12 & 10 & 2\\13& \text{Al} & 13 & 10 & 3 \\14& \text{Si} & 14 & 10 & 4 \\15& \text{P} & 15 & 10 & 5\\16& \text{S} & 16 & 10 & 6\\17& \text{Cl} & 17 & 10 & 7\\18& \text{Ar} & 18 & 10 & 8 \\\end{array}$

The number of protons increases as you go from one element to the next, but the number of inner electrons is constant.

3 0

3 years ago

Mention the significance of dams and irrigation canals?

GarryVolchara [31]

Significance of dams and canals are :- 

Water is stored in dams that are built across rivers. The water is then supplied to nearby towns and cities through pipelines

Water for agricultural purposes is supplied through a system of irrigation canals

hope it helps ~

3 0

2 years ago