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Nataliya [291]
2 years ago
15

What % of original U238 remains after three half lives? 1-50 2-25 3-12.5 4-6.25

Chemistry
1 answer:
Grace [21]2 years ago
7 0

Answer:

12.5

Explanation:

After three half-lives, one eighth (1/2 x 1/2 x 1/2) of the uranium-238 will remain. One-eighth equals 12.5%

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how much heat energy is needed to raise the temperature of 78.4g of aluminum from 19.4 degrees c to 98.6 degrees c.
Iteru [2.4K]

 The heat that is needed  to raise the   temperature  of 78.4 g of aluminium from 19.4 °c to 98.6°c  is    5600.77 j

 <u><em>calculation</em></u>

Heat(Q) = mass(M) x  specific heat capacity (C) x change in temperature(ΔT)


where;

Q=?

M = 78. 4 g

C=0.902 j/g/c

ΔT=98.6°c -19.4°c =79.2°c

Q is therefore = 78.4 g  x 0.902 j/g/c  x 79.2°c  =5600.77 j

7 0
3 years ago
Why do group 7 elements have higher melting and boiling points going down?
Genrish500 [490]

Answer:

this is because the van der waals forces or also known as induced dipole-dipole interactions increase because more electrons are present within an atom as you go down

Explanation:

-

8 0
3 years ago
1. What is the relationship between pressure and volume?
MariettaO [177]

Answer:

An increase in pressure would cause less volume and vice versa. They are inversely proportional.

Explanation:

This is due to Boyle's Law (and because an increase in pressure would increase the force on the container, however, if it's a closed container, it would burst)

<em>Feel free to mark it as brainliest :D</em>

5 0
3 years ago
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As a student , what can you do to help in preventing pollution in your community ?​
aliya0001 [1]

Answer: as a student , i will  do to help in preventing pollution in my  community :

Reduce the number of trips you take in your car.

Reduce or eliminate fireplace and wood stove use.

Avoid burning leaves, trash, and other materials.

Avoid using gas-powered lawn and garden equipment.

Using non-toxic or less toxic chemicals as cleaners, degreasers and other maintenance chemicals. Implementing water and energy conservation practices. Reusing materials such as drums and pallets rather than disposing of them as waste.

Store your household chemicals (including cleaning products, paints, fuel canisters, etc.) as far away as possible from the living space and, if possible, in metal cabinets. Do not store chemicals in areas where you spend most of the time. Also, do not store chemicals in open cabinets or shelves.

Use Public Transportation. Use your vehicle a lot less often. .

Drive Smart. .

Do Regular Car Check-Up. .

Keep Car Tires Properly Inflated. .

Buy Energy-Efficient Vehicles. .

Consider “going green” .

Plant a Garden. .

Use Low-VOC or Water-based Paints.

Avoid smoking indoors (but quitting smoking is the best answer for overall health).

Use craft supplies in well-ventilated areas.

Make sure your gas stove is well-ventilated.

Minimize clutter.

Remove carpeting if possible.

Use a dehumidifier and/or air conditioner to reduce moisture.

How can students help reduce pollution?

Help Recycling

The most obvious things to reuse are plastic, glass, metal, and paper or fabric (paper and organic fabric are made of the same component, cellulose, and are recycled in a similar way). The color-coded trash bins show where each of these components can be put to be recycled in a proper way.

REDUSE ,REUSE , RECYCLE

3 0
2 years ago
Metals react with oxygen to give oxides with the general formula MxOy. What is a balanced chemical equation for the reaction of
katovenus [111]

Answer: 4Fe+3O_2\rightarrow 2Fe_2O_3

Explanation:

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.  

Here iron is having an oxidation state of +3 called as Fe^{3+} cation and oxide O^{2-} is an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral Fe_2O_3.

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

2Fe+3O_2\rightarrow 2Fe_2O_3

8 0
3 years ago
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