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Schach [20]
3 years ago
5

What is meant by the half-life of a radioactive substance

Chemistry
1 answer:
Shtirlitz [24]3 years ago
3 0

Answer:

Explanation:

The half life of a radioactive atom is the time taken for half of the radioactive nuclei to disintegrate. The shorter the half life, the faster a radioactive nuclei decays.

Half life is often expressed as:

                               Half life = \frac{0.693}{λ}

Where λ is the decay constant.

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Which of the following molecules is responsible for transmitting the energy needed by cells
kolbaska11 [484]
Adenosine triphosphate (ATP)
7 0
3 years ago
Read 2 more answers
I need help solving this!
zmey [24]

Answer: Moles of hydrogen required are 4.57 moles to make 146.6 grams of methane, CH_{4}.

Explanation:

Given: Mass of methane = 146.6 g

As moles is the mass of a substance divided by its molar mass. So, moles of methane (molar mass = 16.04 g/mol) are calculated as follows.

Moles = \frac{mass}{molar mass}\\= \frac{146.6 g}{16.04 g/mol}\\= 9.14 mol

The given reaction equation is as follows.

C + 2H_{2} \rightarrow CH_{4}

This shows that 2 moles of hydrogen gives 1 mole of methane. Hence, moles of hydrogen required to form 9.14 moles of methane is as follows.

Moles of H_{2} = \frac{9.14}{2}\\= 4.57 mol

Thus, we can conclude that moles of hydrogen required are 4.57 moles to make 146.6 grams of methane, CH_{4}.

5 0
3 years ago
When the glucose solution described in part A is connected to an unknown solution via a semipermeable membrane, the unknown solu
gtnhenbr [62]

Answer:

The unknown solution had the higher concentration.

Explanation:

When two solutions are separated by a semi-permeable membrane, depending on the concentration gradient between the two solutions, there is a tendency for water molecules to move across the semi-permeable in order to establish an equilibrium concentration between the two solutions. This movement of water molecules across a semi-permeable membrane in response to a concentration gradient is known as osmosis. In osmosis, water molecules moves from a region of lower solute concentration or higher water molecules concentration to a region of higher solute concentration or lower water molecules concentration until equilibrium concentration is attained.

Based on the observation that when the glucose solution described in part A is connected to an unknown solution via a semipermeable membrane, the unknown solution level rises, it means that water molecules have passed from the glucose solution through the semipermeable membrane into the unknown solution. Therefore, the solution has a higher solute concentration than the glucose solution.

3 0
3 years ago
A person's heart beats 72 times a minute. At this rate, how many times does it beat in one hour?
sesenic [268]

At one minute, a persons's heart beats 72 times.

Therefore, in one hour or 60 minutes, a person's heart will beat (60×72) times, i.e., 4320 times

Answer is 4320 times

6 0
3 years ago
8. Bring the balloon in contact with the wall. What happens to the charges in the wall?
Ne4ueva [31]

When the charged balloon is brought near the wall, it repels some of the negatively charged electrons in that part of the wall. Therefore, that part of the wall is left repelled.

<u>Explanation</u>:  

  • Balloons don't stick to walls. However, if you rub the balloon on an appropriate piece of material such as clothing or a wall, electrons are pulled from the other material to the balloon.
  • The balloon now as more electrons than normal and therefore has an overall negative charge. Two balloons like this will repel each other.
  • The other material now has an overall positive charge. Because opposite charges attract, the balloon will now appear to stick to the other material. If you didn't rub the balloon first, it's charge would be neutral and it wouldn't stick to the wall.
7 0
4 years ago
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