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3 years ago

PLEASSE help its homework

Chemistry

2 answers:

tiny-mole [99]3 years ago

8 0

Answer:

What homework? i dont see a picture, can u tell me the question?

Explanation:

Alborosie3 years ago

6 0

There is no picture. It just says please help it’s homework. Sorry! If you want to put it in the comments maby I can help.

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Samples with masses of 5.5 g 2.27 g and 0.8995 g are mixed together. The sum of the masses of the three

Nadusha1986 [10]

Answer:

$m=8.7g$

Explanation:

Hello,

In this case, it is widely known that when measurements with different significant figures are put under mathematical operations, the final result must be displayed with the same amount of significant figures of the shortest measurement, thus, due to the fact that 5.5 g has two significant figures only the result is consequently shown with two significant figures as well as shown down below:

$m=5.5g+2.27g+0.8995g\\\\m=8.6695g$

By rounding the first six to seven due to the fact that the next six is greater than five, according to rounding rules, the result is:

$m=8.7g$

Best regards.

3 0

3 years ago

For an alloy that consists of 91.0 g copper, 111 g zinc, and 7.51 g lead, what are the concentrations (a) of Cu (in at%), (b) of

viktelen [127]

Answer:

$\% Cu=45.2\%\\\\\% Zn=53.6\%\\\\\% Pb=1.2\%$

Explanation:

Hello!

In this case, given the masses of copper, zinc and lead, it is possible to compute the moles via their atomic masses first:

$n_{Cu}=\frac{91.0gCu}{63.55g/mol}=1.432mol\\\\ n_{Zn}=\frac{111gZn}{65.41g/mol}=1.697mol\\\\n_{Pb}=\frac{7.51gPb}{207.2g/mol}=0.0362mol\\$

Now, we compute the atomic percentages as shown below:

$\% Cu=\frac{1.432}{1.432+1.697+0.0362}*100\% =45.2\%\\\\\% Zn=\frac{1.697}{1.432+1.697+0.0362}*100\%=53.6\%\\\\\% Pb=\frac{0.0362}{1.432+1.697+0.0362}*100\%=1.2\%$

Best regards!

4 0

2 years ago

A vial is filled with room temperature water, and blue cold water has been placed at the bottom. A warm water bag sits next to t

MrRa [10]

Explanation:

In the context, a vial which is used in store medical samples is filled with water at room temperature. And the vial is kept on a cold water. Also a water bag containing warm water is kept near the vial.

The cold water kept at the bottom of the vial is having lower kinetic energy while warm water will have higher kinetic energy than the others. Since the water in the vial is at room temperature and it is in touch with the cold blue water, the water in the vial will loose or give its temperature to the cold blue water through conduction as well as convection process since temperature always flows from a hot body towards the cold body.

On the other hand, the warm water placed next tot he vial will give its temperature to the atmosphere.

5 0

3 years ago

The element oxygen has _____ valence electrons. (Input only a whole number, such as 7.) Numerical Answers Expected! Answer for B

navik [9.2K]

Answer:

7 valence electrons.

Explanation:

Oxygen lies in period 2 and group 16 of the periodic table. It is eighth element on the periodic table. Its symbol is O.

Its electronic configuration is given by:

16 = 2,8,6

It has 6 valance electrons. Its valancy is -2. It means can share share and it can gain 2 electron to get stability.