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ollegr [7]
3 years ago
5

How much radium-226 will remain from a 20 gram sample after 4800 years?

Chemistry
1 answer:
ra1l [238]3 years ago
4 0

Answer:

2.5 g mass of Ra-226 will remain after 4800 years.

Explanation:

Given data:

Mass of Ra-226 = 20 g

Sample remain after 4800 years = ?

Solution:

Half life of Ra-226 = 1600 years

Number of half lives passed = T elapsed / half life

Number of half lives passed = 4800 year / 1600 year

Number of half lives passed = 3

At time zero = 20 g

At first half life = 20 g/2 = 10 g

At 2nd half life = 10 g/2 = 5 g

At 3rd half life = 5 g/2 = 2.5 g

Thus, 2.5 g mass of Ra-226 will remain after 4800 years.

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0.250 moles of NaCl is dissolved in 0.850 L of solution. What is the molar concentration?
Nuetrik [128]

Considering the definition of molarity, the molar concentration is 0.294 \frac{moles}{liter}.

Molarity reflects the concentration of a solution indicating the number of moles of solute that are dissolved in a given volume.

The molarity of a solution is calculated by dividing the moles of the solute by the volume of the solution:

molarity=\frac{amount of moles of solute}{volume}

Molarity is expressed in units \frac{moles}{liter}.

In this case, you know:

  • amount of moles of solute= 0.250 moles
  • volume= 0.850 L

Replacing in the definition of molarity:

molarity=\frac{0.250 moles}{0.850 L}

Solving:

molarity= 0.294 \frac{moles}{liter}

Finally, the molar concentration is 0.294 \frac{moles}{liter}.

Learn more about molarity with this example: brainly.com/question/15406534?referrer=searchResults

6 0
3 years ago
An isotope undergoes radioactive decay. The new isotope that forms has an atomic number that is 2 less than the original isotope
jeka57 [31]
It is an alpha decay because when this phenomena occurs an atomic nucleus emits an alpha particle (helium nucleus) and consequentially decays into another atom with a mass number that is reduced by four an atomic number that is reduced by 2 two. The helium atom consists of two protons and two neutrons.

Therefore, the answer is <span>alpha decay because alpha particles have two protons and two neutrons</span>
3 0
3 years ago
Read 2 more answers
A piece of iron metal is heated to 155 degrees C and placed into a calorimeter that contains 50.0 mL of water at 18.7 degrees C.
Korvikt [17]

Answer:

D = 28.2g

Explanation:

Initial temperature of metal (T1) = 155°C

Initial Temperature of calorimeter (T2) = 18.7°C

Final temperature of solution (T3) = 26.4°C

Specific heat capacity of water (C2) = 4.184J/g°C

Specific heat capacity of metal (C1) = 0.444J/g°C

Volume of water = 50.0mL

Assuming no heat loss

Heat energy lost by metal = heat energy gain by water + calorimeter

Heat energy (Q) = MC∇T

M = mass

C = specific heat capacity

∇T = change in temperature

Mass of metal = M1

Mass of water = M2

Density = mass / volume

Mass = density * volume

Density of water = 1g/mL

Mass(M2) = 1 * 50

Mass = 50g

Heat loss by the metal = heat gain by water + calorimeter

M1C1(T1 - T3) = M2C2(T3 - T2)

M1 * 0.444 * (155 - 26.4) = 50 * 4.184 * (26.4 - 18.7)

0.444M1 * 128.6 = 209.2 * 7.7

57.0984M1 = 1610.84

M1 = 1610.84 / 57.0984

M1 = 28.21g

The mass of the metal is 28.21g

3 0
3 years ago
Neutral atoms of the same element can differ in their number of
konstantin123 [22]

Answer:

a. neutron

Explanation:

A neutral atom has the same number of protons and electrons because in order for it to be a neutral atom the charges must be the same.

a neutron has no charge therefore it can be different then the number of protons and electrons in a neutral atom as it won't affect the charge.

7 0
2 years ago
What process uses a set of skills to answer questions or to test ideas about the natural world
Anit [1.1K]

Answer:

<em>Hello! </em>

Explanation:

The scientific inquiry is a process that uses a set of skills to answer question or to test ideas about the natural world.

<em>Hope this helps! ^^</em>

<em>From: Deku! <3</em>

7 0
4 years ago
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