Answer:
Option A. 11
Explanation:
The atomic number of an element does not change.
Recall:
Atomic number = proton number
If the atom is neutral, then,
Proton number = electron number
Since the element is sodium, then, the atomic number of sodium–25 is 11.
Also, we were told to obtain the electrons of a neutral atom of sodium–25
Therefore,
Atomic number = proton number = 11
Since the atom is neutral,
Proton number = electron number = 11
Answer:
10 m/s
Explanation:
Kinetic energy=
mv² where m is mass and v is velocity.
We have to make v the subject so we should rearrange the equation
K=
mv²
v²=
(use algebra)
v²= 7/0.5×0.140
v²=100
v=√100
v=10 m/s
We can confirm this by using the kinetic energy formula.
K=
×0.140×10²
K= 7 J
Hence it is proved that velocity is 10 m/s
It is called an "orbit". Repeating and regular path that one object in space takes around in another one. This object ca be satellite or natural satellite like our moon. Planets, comets, asteroids and other objects in the solar system orbit the sun. Orbits come in different forms or shapes. All orbit are elliptical which means they are ellipse, similar to oval.
Answer:
t=20s
Explanation:
To solve this problem we must apply the first law of thermodynamics, which indicates that the energy that enters a system is the same that must come out, resulting in the following equation
For this problem we will assume that the water is in a liquid state, since it is a domestic refrigerator
q=m.cp.(T2-T1)
q=heat
m=mass of water =600g=0.6Kg
cp=
specific heat of water=4186J/kgK
T2=temperature in state 2=20°C
T1=temperature in state 1=0°C
solving:
q=(0.6)(4186)(20-0)=50232J
A refrigerator is a device that allows heat to be removed to an enclosure (Qin), by means of the input of an electrical energy (W) and the heat output (Qout), the coefficient of performance COP, allows to know the ratio between the heat removed ( Qin) and the added electrical power (W), the equation for the COP is

To solve this exercise we must know the value of the heat removed to the water (Qin)
solving for Qin
Qin=(COP)(Win)
Qin=(5)(500W)=2500W
finally we remember that the definition of power is the ratio of work over time
w=work
p=power=500w

NO. although the arrangement of the atoms will change, the total number stays constant.