The mineral manganosite, manganese(ll) oxide, crystallizes in the rock salt structure the face-centered structure adopted by NaCl) with a density of 5.365 g/cm'. Find the unit cell edge length of manganosite. A. 444.5 pm
B. 352.8 pm
C. 280.0 pm
D. 368.2 pm
E. 417.9 pm

A. 444.5 pm

Explanation:

We know that:

i.e.

in a face-centered cubic crystal, the number of atoms per unit cell is (n) = 4

The molar mass of manganese (II) oxide

Density is given as 5.365 g/cm³

Avogadro constant = 6.023 × 10²³ atoms/mol

∴

Making th edge length "a" the subject, we get:

a = 4.445 × 10⁻⁸ cm

a = 444.5 pm

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.