Density gives mass of object per volume...... Here, density is given 8.90 g/cm3 therefore, per cubic centimeter contains 8.90 g Ni. mole of Ni = mass / atomic mass = 8.90 / 58.6934 = 0.1516 mole number of atoms: mole * 6.022 * 10^23 = 0.1516 * 6.022 * 10^23 = 0.9129 * 10^23 = 0.9 * 10^23 (approx.)
Answer:

Explanation:
Balanced equation: CO(g) + H₂O(g) ⟶ CO₂(g) + H₂(g)
We can calculate the enthalpy change of a reaction by using the enthalpies of formation of reactants and products

(a) Enthalpies of formation of reactants and products

(b) Total enthalpies of reactants and products

(c) Enthalpy of reaction
Answer:
P₂ = 2.7 atm
Explanation:
Given data:
Initial temperature = 30°C
Initial pressure = 3.00 atm
Final temperature = -5°C
Final pressure = ?
Solution:
Initial temperature = 30°C = 30 + 273 = 303 K
Final temperature = -5°C = -5 + 273 = 268 K
According to Gay-Lussac Law,
The pressure of given amount of a gas is directly proportional to its temperature at constant volume and number of moles.
Mathematical relationship:
P₁/T₁ = P₂/T₂
Now we will put the values in formula:
3.0 atm / 303 K = P₂/268 K
P₂ = 3.0 atm × 268 K / 303 K
P₂ = 804 atm. K /293 K
P₂ = 2.7 atm
For your second question its Diamonds,Rubys, Emeralds.
And for your first question its :Minerals are natural: These substances that form without any human help.
Minerals are solid: They don't droop or melt or evaporate.
Minerals are inorganic: They aren't carbon compounds like those found in living things.
Minerals are crystalline: They have a distinct recipe and arrangement of atoms.