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attashe74 [19]
3 years ago
6

Africa has _____ countries.

Physics
2 answers:
Aliun [14]3 years ago
3 0

According to the United Nations, there are <em>54 </em>countries in Africa today (late 2018).

Nutka1998 [239]3 years ago
3 0

Answer:56

Explanation:count them

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How do plants absorb light energy from sun
brilliants [131]

There are plant cells called chloroplasts, plants leave chloroplasts which have chlorophyll that capture and absorb light energy from the sun.

3 0
3 years ago
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If we increase the distance traveled when doing work, and keep all other factors the same, what will happen?
stepladder [879]

Answer: D

Explanation:

A -amount of work

F-force

s-distance

If you keep same Force(F) and increase distance(s), amount of work will increase, according to:

A=F*s

8 0
4 years ago
Measurements show that the enthalpy of a mixture of gaseous reactants decreases by during a certain chemical reaction, which is
snow_tiger [21]

The given question is incomplete. The complete question is as follows.

Measurements show that the enthalpy of a mixture of gaseous reactants decreases by 338 kJ during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that 187 kJ of work is done on the mixture during the reaction. Calculate the change in energy of the gas mixture during the reaction. Be sure your answer has the correct number of significant digits. Is the reaction exothermic or endothermic ?

Explanation:

The given data is as follows.

    Change in enthalpy (\Delta H) = -338 kJ (as it is a decrease)

    Work done = 187 kJ,

    Change in energy (\Delta E) = ?

Now, according to the first law of thermodynamics the formula is as follows.

          \Delta H = \Delta E + P \Delta V

Hence, putting the given values into the above formula as follows.

        \Delta H = \Delta E + P \Delta V

Also, we know that W = P \Delta V

so,           \Delta H = \Delta E + W      

              -338 kJ = \Delta E + 187

              \Delta E = -151 kJ

Thus, we can conclude that the change in energy of the gas mixture during the reaction is -151 kJ.

5 0
3 years ago
(a) Compute the radius r of an impurity atom that will just fit into an FCC octahedral site in terms of the atomic radius R of t
ratelena [41]

Answer:

radius r is  0.414 R

Explanation:

Given data

FCC octahedral site

atomic radius R

to find out

radius r

solution

we know that at FCC octahedral

length of side = 2 R + 2r

and by pythagorean theorem

a = 2√2R

here a = 2R + 2r

so 2R + 2r = 2√2R

so r = ( √2R )- R

r = 0.414 R

so  radius r is  0.414 R

5 0
3 years ago
We’ve already investigated this problem with one spring scale in Think About 34.1. Now, imagine you have two spring scales, A an
Debora [2.8K]

Answer:

Explained

Explanation:

1.Each of the spring scale will read 10N,considering acceleration due to gravity as 10 m/s^2

2.Each of the spring scale will read 10N because each string exerts a force of 10 N to counterbalance the force of 1 kg mass attached to it. This means the tension on the both side of the string is 10 N. So the scale will read 10 N. Also as spring balances are attached in series and kept on table so both spring balances will read same readings.

5 0
3 years ago
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