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2.7 days

## How long does it take a 180 g sample of AU-198 to decay to ⅛ its original mass?

How long does it take a 180 g sample of Au-198 to decay to 1/8 ofits original mass? The half-life of Au-198 is 2.69 days.

## How long does it take a 100g sample of AU-198 to decay to 6.25 g?

100 g of Au-198 would have a half life of 2.7 days.

## How much of a radioactive sample remains after each half life?

The quantity of radioactive nuclei at any given time will decrease to half as much in one half-life. For example, if there were 100g of Cf-251 in a sample at some time, after 800 years, there would be 50g of Cf-251 remaining. After another 800 years (1600 years total), there would only be 25g remaining.

## What percentage of a radioactive sample remains after 5 half lives?

Thus a first-order chemical reaction is 97% complete after 5 half-lives and 100% complete after 10 half-lives.

## Will the amount of radioactive material ever reach zero?

One funny property of exponential decay is that the total mass of radioactive isotopes never actually reaches zero. Realistically, there are only a fixed number of atoms in a radioactive sample, and so the mass of an isotope will eventually reach zero as all the nuclei decay into another element.

## What is the state of a radioactive sample after 2 half-lives have passed?

After 1 half life , clearly HALF of the original isotope remains. And after TWO half-lives, a HALF + HALF of a HALF , i.e. 34 of the original mass has decayed.

## How long will it take for 30 g of 222Rn to decay to 7.5 g?

14 Cards in this Set

Compared to the mass and the penetrating power of an alpha particle, a beta particle has Less mass and greater penetrating power
How long will it take for 30g of 222Rn to decay to 7.5g? 30->15->7.5 2(3.823d) 7.646d
For any element, an unstable isotope is called Radioisotopes

## How do you calculate half lives?

How to calculate the half-life

1. Determine the initial amount of a substance.
2. Determine the final amount of a substance – for instance, N(t) = 2.1 kg .
3. Measure how long it took for that amount of material to decay.
4. Input these values into our half-life calculator.

## What is the fraction equivalent of 2 half lives?

Half-life

Number of half-lives elapsed Fraction remaining Percentage remaining
2 1⁄4
3 1⁄8 .5
4 1⁄16 .25
5 1⁄32 .125

## Can a half-life be a decimal?

At this point 0.5 of the original amount remains. 0.5 expressed as a percentage is 50%. However, please be aware that it is the decimal amount that will be used in the various calculations, not the percentage. Just below are the amounts remaining after 2, 3, and 4 half-lives.

## What is element Half-Life?

The half-life of a substance is the time it takes for half of the substance to decay. The word “half-life” was first used when talking about radioactive elements where the number of atoms get smaller over time. Half-life is the expected value when half the number of atoms have decayed.

## How do you solve fractions with variables?

Solve equations by clearing the Denominators

1. Find the least common denominator of all the fractions in the equation.
2. Multiply both sides of the equation by that LCD.
3. Isolate the variable terms on one side, and the constant terms on the other side.
4. Simplify both sides.

## What are the 7 types of fraction?

The six kinds of fractions are, proper fractions, improper fractions, mixed fractions, like fractions, unlike fractions and equivalent fractions.

## How do you simplify fraction?

How to Reduce Fractions

1. Write down the factors for the numerator and the denominator.
2. Determine the largest factor that is common between the two.
3. Divide the numerator and denominator by the greatest common factor.
4. Write down the reduced fraction.

## How do you solve fraction problems with different denominators?

If the denominators are not the same, then you have to use equivalent fractions which do have a common denominator . To do this, you need to find the least common multiple (LCM) of the two denominators. To add fractions with unlike denominators, rename the fractions with a common denominator. Then add and simplify.

## What do you call fractions with different denominators?

Fractions with different denominators are called the unlike fractions. For example, 2/3, 4/9, 6/67, 9/89 are unlike fractions.

## How do you add and subtract fractions with different denominators?

Make their denominators equal using the concept of least common multiple. Then subtract their numerators accordingly. Rewrite each fraction to its equivalent fraction with a denominator equal to the LCM = 30, then subtract their numerators. Make sure to reduce your answer to the lowest term.

## How do you add mixed numbers with different denominators?

1. To add mixed numbers, we first add the whole numbers together, and then the fractions.
2. If the denominators of the fractions are different, then first find equivalent fractions with a common denominator before adding.
3. Subtracting mixed numbers is very similar to adding them.

## How do you add mixed numbers step by step?

The steps are the same whether you’re adding or subtracting mixed numbers:

1. Find the Least Common Denominator (LCD)
2. Find the equivalent fractions.
3. Add or subtract the fractions and add or subtract the whole numbers.

## How do you find a common denominator?

To make the denominators the same we can: Multiply top and bottom of each fraction by the denominator of the other. We simplified the fraction 2032 to 1016 , then to 58 by dividing the top and bottom by 2 each time, and that is as simple as it can get!

210

## What is the lowest common multiple mean?

The lowest common multiple of two numbers is the smallest whole number which is a multiple of both. Teachers may introduce this concept to more able Year 6 children. Quick reminder: a multiple is a number that can be divided by another number a certain number of times without a remainder.

## What is the LCD of 1 3 and 2 7?

Therefore, the least common denominator (LCD) is 21.

2021-06-17