Explanation:
Given that,
Mass of metal cube, m = 20 g
Volume of cube, V =5 mL
We need to find the density of the cube. Mass per unit volume equals density.

So, the density of the cube is 4 g/ml.
We know that the density of Aluminium is 4 g/mL.
So, the cube is not Aluminium cube.
Density
=mass÷volume
=277÷38
=7.29 g/cm3
Answer:
There are no unpaired electrons.
Explanation:
There are no unpaired electrons in the Lewis symbol for a nitride ion(
).The nitride ion has a charge of -3. The negative charge on the Nitride ion indicates a gain in electrons . Nitrogen has 5 valence electrons that is the number of electrons that are in its outer shell .The total number of electrons that the nitride ion has is equal to 5+3 = 8 electrons . Electrons usually appear in pairs and obey the octet rule therefore the nitride ion has four electron pairs no unpaired electrons.
Answer: 3 times as much the potential energy
Explanation:
Potential energy is the energy possessed by an object by virtue of its position.

m= mass of object
g = acceleration due to gravity
h = height of an object
When same object with same is lifted from 10 feet to 30 feet. The height has increased 3 times , thus the potential energy will also get 3 times as much.
Cu ions plus EDTA2- ->cu(EDTA)2- plus 2H-
number of moles of CU ions used which is equal to molarity multiplied by volume in litres
that is 50xo.o2 divided by 1000 that is 0.001moles
Since ratio is 1:1 the moles of EDTA is also0.001moles
volume of EDTA is 0.001 divided by 0.0510m which is 0.0196 litres in ml is 0.0196x1000 which is 19.61ml