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Leokris [45]
3 years ago
12

WORTH 20 POINTS HELP PLEASE

Chemistry
1 answer:
Damm [24]3 years ago
5 0

Answer:

The answers to your questions are below

Explanation:

Physical change is when matter changes its form but is still the same substance.

Chemical change is when matter changes its composition.

iron and oxygen from rust  It's a chemical change because iron and oxygen form a new compound different from the reactants.

iron is denser brightly when ignited . This is a chemical property because iron reacts with oxygen.

oil and water do not mix it's a physical change, oil and water are in touch but they do not react.

mercury melts at -39°C it's a physical property because mercury changes from solid to liquid but it still is mercury.

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When an acid reacts with a base what compounds are formed?
vazorg [7]
It's usually water and a type of salt take the reaction between hydrochloric acid and sodium hydroxide HCl(aq)+NaOH(aq) yeilds NaCl(aq) and H2O(l) 
4 0
3 years ago
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Which two elements have chemical properties that are most similar?
masya89 [10]

Answer:

Li and Na

Explanation:

5 0
3 years ago
What is an echo? (1 point)
zaharov [31]

Answer:

The reflection of sound waves

Explanation:

An echo is a reflection of sound that bounces of of one thing to another.

4 0
3 years ago
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Which is a positive effect of the technology advance of going from a compass to a gps
egoroff_w [7]

Answer:

Compass - Gps                              

Explanation:

I belive the pro's                                      and cons are

                                         GPS             you are trusting a little man made device

the direction you                               to give you directions

are going on                                        and that it won't break or die

a device not a paper map

                                                Compass

You can see north east south and              it is usually carefully crafted for                                                                                                                                                                          o                                                                     outdoors but it has no roads and

west on the compass and                          if given no directions, extremely

you can see the roads follow directions                  confusing until you learn it

like go south then east.

4 0
3 years ago
Some radioactive nuclides have very short half-lives, for example, I-31 has a half-life of approximately 8 days. Pu-234, by comp
lorasvet [3.4K]

Answer:

Here's what I find.

Explanation:

Iodine-131

Iodine-131 is both a beta emitter and a gamma emitter.

_{53}^{131}\text{I}\longrightarrow \, _{54}^{131}\text{Xe} +\, _{-1}^{0}\text{e} +\, _{0}^{0}\gamma

About 90 % of the energy is β-radiation and 10 % is γ-radiation. Both forms are highly energetic.

The main danger is from ingestion. The iodine concentrates in thyroid gland, where the β-radiation destroys cells up to 2 mm from the tissues that absorbed it.

Both the β- and γ-radiation cause cell mutations that can later become cancerous. Small doses, such as those absorbed from the nuclear disasters in the Ukraine and Japan, can cause cancers years after the original iodine has disappeared.

Plutonium-239

Plutonium-239 is an alpha emitter.

_{94}^{239}\text{U} \longrightarrow \, _{92}^{235}\text{Xe} + \, _{2}^{4}\text{He}

Alpha particles cannot penetrate the skin, so external exposure isn't much of a health risk.

However, they are extremely dangerous when they are inhaled and get inside cells. They travel first to the blood or lymph system and later to the bone marrow and liver, where they cause up to 1000 times more chromosomal damage than beta or gamma rays.

It takes about 20 years for plutonium to be eliminated from the liver around 50 years for from the skeleton, so it has a long time to cause damage.

6 0
3 years ago
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