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ziro4ka [17]
3 years ago
9

an atom has 79 protons, 78 electrons and a mass number of 118. how many neutrons does this atom have​

Chemistry
1 answer:
igomit [66]3 years ago
4 0

Answer:

39

Explanation:

Electrons weigh almost nothing, so their mass doesn't really matter for these types of problems. Just subtract 118-79 to find the remaining mass which is for the neutrons.

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If the radius of copper is 0.128 nm, what is the pd of the (100) plane for copper in m-2?
kolbaska11 [484]

Copper has a FCC i.e. face centered cubic crystal structure. The 100 plane is essentially a planar section of the cubic cell where 4 Cu atoms occupy the 4 corners of the plane along with 1 Cu atom at the center of that plane. Each of the Cu atoms in the corners is shared by 4 adjacent unit cells. Thus, there are 2 Cu atoms present in the 100 plane (4*1/4 + 1 = 2).

Now, the planar density PD along the 100 plane is given as:

PD(100) = # atoms in the 100 plane/Area of 100 plane

            = \frac{2}{8R^{2} }

Here R = radius = 0.128 nm = 0.128*10^{-9} m

PD = \frac{2}{8*(0.128*10^{-9}) ^{2} } = 1.526*10^{19} m^{-2}

6 0
3 years ago
How would understanding the properties of matter be helpful in other fields of study besides chemistry?
erma4kov [3.2K]
Matter is the basic unit of all things in the world, whether living or nonliving. It is not only useful in chemistry, but also to other fields of science like physics. Physics deals with motion, so it has something to do with matte especially the movement of molecules for solids and fluids.
5 0
3 years ago
Read 2 more answers
How much heat is absorbed by a 2000 g granite rock as energy from the sun causes its temperature to change from 10°C to 29°C?
emmainna [20.7K]

Answer:

None of the options are correct. The correct answer is 30020J

Explanation:

Data obtained from the question include:

Mass (M) = 2000g

Initial temperature (T1) = 10°C

Final temperature (T2) = 29°C

Change in temperature (ΔT) = T2 - T1 = 29°C - 10°C = 19°C

Heat (Q) =?

Specific heat capacity (C) of granite = 0.79J/g°C

Applying the equation Q = MCΔT, the heat absorbed by the granite rock can be obtained as follow:

Q = MCΔT

Q = 2000 x 0.79 x 19

Q = 30020J

3 0
3 years ago
Which statement describes what happens when somebody slaps their hand on a wall?
laiz [17]

Answer:

B. Wall applies equal reaction force on hand

Explanation:

This is newton's third law. You push something, that something pushes you back with same force. The direction is opposite, so if I push a wall, the wall pushes me back with same force just in opposite direction (so wall towards me). This is why option A is incorrect b/c it says force in same direction as wall. C and D talk about unequal force which is incorrect.

7 0
2 years ago
Mg(OH)2 + 2HNO3 → Mg(NO3)2 + 2H20
LenaWriter [7]

Answer:

A. 1350

You multiply 18.21HNO3* 1mol MgN2O6 * 148.30MgN2O6

Then divide it by the 2mol HNO3 to get 1350

3 0
3 years ago
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