The energy of an electron in a hydrogen atom is:
<span>E= (-2.179 x 10 ^-18 J)(1/n^2)
</span>where n is the principle energy level of the electron.
<span>
E= (-2.179 x 10 ^-18 J)(1/4)
</span><span>E= -2.179 x 10 ^-18 J
</span>E = -5.4 <span>x 10 ^-19 J</span>
Lead is a chemical element with the symbol Pb (from the Latin plumbum) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point.
Answer:
4 sublevels are completely filled.
Explanation:
Magnesium is present in group 2.
Its atomic mass is 24 g/mol.
Its atomic number is 12.
It is alkaline earth metal.
Electronic configuration of Mg:
Ma₁₂ = 1s² 2s² 2p⁶ 3s²
From above given electronic configuration we can see all sublevels are completely filled.
The 1st energy level have one sub level (1s) which is completely filled, 2nd energy level have 2 sublevel (2s and 2p) and 3rd energy level have one sublevel (3s) completely filled. So all are completely filled.
Answer: The correct option is D.
Explanation: We are given two gas molecules with different masses. The collision between them is elastic, hence the Total Kinetic energy of the system is conserved.
Initial Kinetic Energy:
Final Kinetic Energy:
where,
= mass of first molecule
= mass of second molecule
= initial velocity of first molecule
= initial velocity of second molecule
= final velocity of first molecule
= final velocity of second molecule
Elastic Collision:
That is,
.....(1)
We are given in the question that the final velocity of first molecule is decreased by 1/4, which means:
Putting this value in equation 1 , we get
taking on other side, we get
From the above relation, it is visible that the velocity change of the second molecule depends on both mass and velocity of the first molecule.
Answer:
I'm not 100% sure but I believe it is the first or last
there should be three y's and one x but I can't remember the order. my gut goes with the top one