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2 years ago

Social Studies 3rd Period

Chemistry

1 answer:

docker41 [41]2 years ago

7 0

Answer:

The answer is A, B, and D

Explanation:

A: China burned coal more than wood for heat.

B: Marco Polo wrote about a new energy source from China.

D: Marco Polo helped spread technology and ideas all through out Europe.

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How many images will be formed when two plane mirrors are inclined at an angle of 45 degree

insens350 [35]

Answer:

7 Images

Explanation:

n = 360 / a - 1 = 360 / 45 - 1 = 8-1= 7

(Based on multiple reflections)

I hope im right!!

6 0

2 years ago

Which of the following functional groups acts most like an acid in water? A) carboxyl B) amino C) carbonyl D) hydroxyl.

Anestetic [448]

Answer : A - carboxyl group.

The carbon in the carboxyl group is bonded to a hydroxyl group and also it is double bonded to an oxygen group.

The carboxyl group when it is dissolved in a solution donates it's hydrogen ion(H+ ion). When it is dissolved in water, the carboxyl group loses its H+ ion to form negatively charged ion.

RCOOH + H2O⇄RCOO- + H3O+

Thus the carboxyl group act as an acid when dissolved in water.

8 0

3 years ago

Water’s boiling point would be close to

aleksandrvk [35]

Waters boiling point is 100°C and 212°F

4 0

2 years ago

When 1.045 g of CaO is added to 50.0 mL of water at 25.0 °C in a calorimeter, the temperature of the water increases to 32.3 °C.

Rus_ich [418]

Answer:

1.71 kJ/mol

Explanation:

The expression for the calculation of the enthalpy change of a process is shown below as:-

$\Delta H=m\times C\times \Delta T$

Where,

$\Delta H$ is the enthalpy change

m is the mass

C is the specific heat capacity

$\Delta T$ is the temperature change

Thus, given that:-

Mass of CaO = 1.045 g

Specific heat = 4.18 J/g°C

$\Delta T=32.3-25.0\ ^0C=7.3\ ^0C$

So,

$\Delta H=1.045\times 4.18\times 7.3\ J=31.88713\ J$

Also, 1 J = 0.001 kJ

So,

$\Delta H=0.03189\ kJ$

Also, Molar mass of CaO = 56.0774 g/mol

$Moles=\frac{Mass}{Molar\ mass}=\frac{1.045}{56.0774}\ mol=0.01863\ mol$

Thus, Enthalpy change in kJ/mol is:-

$\Delta H=\frac{0.03189}{0.01863}\ kJ/mol=1.71\ kJ/mol$

8 0

2 years ago

In which of the following locations are bacteria often found?

djyliett [7]

Answer:

in the air and soil

in drinking water

on and inside the human body

Explanation: Hope that helps

7 0

2 years ago