A) 21
Explanation:
The difference between the number of electrons in an atom of selenium and the number electrons in an atom of Aluminium is 21;
The number of electrons in Aluminium is 13
Selenium is 34
Since the atoms are considered here, their atomic number, number of protons and number of electrons are the same.
It is only when we are considering ions that the number of electrons differ from the atomic number/ number of protons.
Difference = 34 - 13 = 21
We clearly see that selenium is 13 electrons more than aluminium.
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Answer:
From 22.9 g of HF 0.575 moles of tin(II) fluoride are produced.
Explanation:
Given data:
Moles of tin(II) fluoride produced = ?
Mass of hydrogen fluoride react = 22.9 g
Solution:
Chemical equation:
SnO + 2HF → SnF₂ + H₂O
Number of moles of HF:
Number of moles = mass/ molar mass
Number of moles = 22.9 g/ 20 g/mol
Number of moles = 1.15 mol
Now we will compare the moles of SnF₂ with HF.
HF : SnF₂
2 : 1
1.15 : 1/2×1.15 = 0.575 mol
Thus, from 22.9 g of HF 0.575 moles of tin(II) fluoride are produced.
Answer:
Potential energy
Explanation:
When an object is moving its called Potential energy.
When an object is not moving it is called kinetic energy.
1. False
2. True
3. True
4. False
5. True.
6. False.
7. True.
8. False.
9. False.
10. True.
11. False.
<h3><u>Explanation</u>:</h3>
A wave is a disturbance in a medium which can propagate through a medium. But the net displacement of the medium remains zero.
The spreading of the wave from a slit or hole is proved through the double slit experiment showing interference between the two waves. So they do spread by passing through a hole.
A longitudinal wave is what is seen when a stone is thrown into a pond. The ripples created are the compression points and the areas between the two ripple is called the rarefaction point.
Amplitude is defined as the maximum displacement of a particle in wave from its mean position. So its not distance between two compression points.
2nd law of reflection states that the angle of incidence is equal to angle of reflection.
An electromagnetic wave doesn't need a matter to get transferred. Its the electric field and magnetic field vibrating at same interval but in 90°to each other.
Mechanical wave needs matter to transfer energy. So it cannot travel through space.
Decibel is the unit of intensity of sound. Unit of frequency is hertz or cps.
Answer:
2.5 grams of of water is consumed by the reaction of 6.2 g of carbon dioxide.
Explanation:
Moles of carbon dioxide =
According to reaction , 6 moles of carbon dioxide reacts with 6 moles of water.
Then 0.1410 moles of carbon dioxide will react with:
of water.
Mass of 0.14109 moles of water = 0.1410 mol × 18 g/mol = 2.536 g ≈ 2.5 g
2.5 grams of of water is consumed by the reaction of 6.2 g of carbon dioxide.