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3 years ago

14

Coal contains _______ energy. A) light B) kinetic C) chemical D) mechanical

2 answers:

olga55 [171]3 years ago

7 0

The answer is C) Chemical because it’s always after them

ololo11 [35]3 years ago

3 0

C chemical since it is after all made of chemicals

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Which of the following methods separates a homogeneous solution by spinning the solution very fast?

Zolol [24]

Answer:

<em> The answer is </em><u><em>(D) Magnetism</em></u>

The methods separates a homogeneous solution by spinning the solution very fast is magnetism.

7 0

3 years ago

Read 2 more answers

Which of the following best describes a double-replacement reaction?

Mariulka [41]

The answer is B for apex!

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4 years ago

Balance the following redox equation in acidic solution using the smallest integers possible and select the correct coefficient

romanna [79]

Answer:

Coefficient of $H^{+}(aq)$ is more than 4

Explanation:

Oxidation: $Sn^{2+}(aq)\rightarrow Sn^{4+}(aq)$

Balance charge: $Sn^{2+}(aq)-2e^{-}\rightarrow Sn^{4+}(aq)$ ......(1)

Reduction: $Cr_{2}O_{7}^{2-}(aq)\rightarrow Cr^{3+}(aq)$

Balance Cr: $Cr_{2}O_{7}^{2-}(aq)\rightarrow 2Cr^{3+}(aq)$
Balance O and H in acidic medium: $Cr_{2}O_{7}^{2-}(aq)+14H^{+}(aq)\rightarrow 2Cr^{3+}(aq)+7H_{2}O(l)$
Balance charge: $Cr_{2}O_{7}^{2-}(aq)+14H^{+}(aq)+6e^{-}\rightarrow 2Cr^{3+}(aq)+7H_{2}O(l)$ .......(2)

$[3\times Equation-(1)]+Equation(2)$ gives balanced equation:

$3Sn^{2+}(aq)+Cr_{2}O_{7}^{2-}(aq)+14H^{+}(aq)\rightarrow 3Sn^{4+}(aq)+2Cr^{3+}(aq)+7H_{2}O(l)$

So coefficient of $H^{+}(aq)$ is more than 4

3 0

3 years ago

A laser emits a green light with wavelength of 515 nm. Calculate the frequency of this light.

pentagon [3]

Answer:

$Frequency=5.83\times 10^{14}\ Hz$

Explanation:

The relation between frequency and wavelength is shown below as:

$c=frequency\times Wavelength$

c is the speed of light having value $3\times 10^8\ m/s$

Given, Wavelength = 515 nm

Also, 1 m = $10^{-9}$ nm

So,

Wavelength = $515\times 10^{-9}$ m

Thus, Frequency is:

$Frequency=\frac{c}{Wavelength}$

$Frequency=\frac{3\times 10^8}{515\times 10^{-9}}\ Hz$

$Frequency=5.83\times 10^{14}\ Hz$

6 0

3 years ago

A student measures the mass of an object and obtains three values: 21.57 g,

Cerrena [4.2K]

Answer:

21.65

Explanation:

The average = total divided by the number of readings

21.57

22.04

<u>21.35</u>

Total = 64.96

Average = 64.96 / 3 = 21.65

6 0

4 years ago