Answer:
Monatomic molecule
Explanation:
Each helium atom has 2 electrons, which is already the maximum no. of electrons that can fit in the first electron shell. When the outermost electron shell is full (2 for the first layer, 8 for others), the atom is stable.
Helium atom itself is already stable, so it doesn't need to combine with another helium atom to form a molecule, hence we call it monatomic.
The statement which is true is
metals lose electrons to become cations
<u><em>Explanation</em></u>
- metals tends to loss electrons to attain noble gas electrons configuration.
- When metal loses electrons they form a positive charged ions.
- The positively charged ion is known as cations.
- for example sodium metal (Na) loses 1 electron to form a cation with a charge of positive 1 ( Na^+)
<span>K3Fe(CN)6
K - 3 atoms
Fe - 1 atom
C - 6 atoms
N - 6 atoms
Altogether : 3+1+6+6= 16 atoms</span>
<u>Analysing the Question:</u>
We are given a 250 mL solution of 0.5M K₂Cr₂O₇
Which means that we have:
0.5 Mole in 1L of the solution
0.125 moles in 250 mL of the solution <em>[dividing both the numbers by 4]</em>
<em />
<u>Mass of K₂Cr₂O₇ in the given solution:</u>
Molar mass of K₂Cr₂O₇(Potassium Dichromate) = 194 g/mol
<em>we know that we have 0.125 moles in the 250 mL solution provided</em>
Mass = Number of moles * Molar mass
Mass = 0.125 * 194
Mass = 36.75 grams
Answer:
Explanation:
M(s) → M (g ) + 20.1 kJ --- ( 1 )
X₂ ( g ) → 2X (g ) + 327.3 kJ ---- ( 2 )
M( s) + 2 X₂(g) → M X₄ (g ) - 98.7 kJ ----- ( 3 )
( 3 ) - 2 x ( 2 ) - ( 1 )
M( s) + 2 X₂(g) - 2 X₂ ( g ) - M(s) → M X₄ (g ) - 98.7 kJ - 2 [ 2X (g ) + 327.3 kJ ] - M (g ) - 20.1 kJ
0 = M X₄ (g ) - 4 X (g ) - M (g ) - 773.4 kJ
4 X (g ) + M (g ) = M X₄ (g ) - 773.4kJ
heat of formation of M X₄ (g ) is - 773.4 kJ
Bond energy of one M - X bond = 773.4 / 4 = 193.4 kJ / mole
