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mol/dm³ is measure for molarity
7.55 x 6.02 x 10²³ = 4.55 x 10²⁴ atoms
The electron group arrangement of NO²⁻is trigonal planar. The molecular shape is bent, and the bond angle is 120°.
<h3>What is the molecular shape of a compound?</h3>
The molecular geometry of the compound shows the position of nuclei and the electron of the compound. It shows how the joining of electrons and nuclei makes the shape of the compound.
Like here, the shape of nitrite is bent with lone pair which is shown by Lewis's structure The bond angle will be the distance between the nuclei of the neighbor atoms.
Thus, the electron geometry arrangement of nitrite is trigonal planer with a bent shape and the bond angle will be 120°.
To learn more about molecular geometry, refer to the link:
brainly.com/question/7558603
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Answer:
A concentrated acid is an acid which is in either pure form or has a high concentration. Laboratory type sulfuric acid (about 98% by weight) is a concentrated (and strong) acid. A dilute acid is that in which the concentration of the water mixed in the acid is higher than the concentration of the acid itself.
Explanation:
Concentrated acid - Those acids which are pure or have very high concentration in water are called as concentrated acids. For example concentrated Hydrochloric acid (HCl) and concentrated Sulphuric acid are examples of concentrated acids.
When mixture of NaCl and Al₂(SO₄)₃ is allowed to react with excess NaOH, only Al₂(SO₄)₃ reacts with it and NaCl does not react with NaOH due to presence of common ion (Na⁺). On reaction gelatinous precipitate of aluminium hydroxide [Al(OH)₃] is produced. The balanced chemical reaction is represented as-
Al₂(SO₄)₃ + 6NaOH → 2Al(OH)₃ + 3Na₂SO₄
On this reaction, 0.495 g = 0.495/78 moles =6.346 X 10⁻³ moles of Al(OH)₃.
As per balanced reaction, two moles of Al(OH)₃ is produced from one mole Al₂(SO₄)₃. So, 6.346 X 10⁻³ moles of Al(OH)₃ is produced from (6.346 X 10⁻³)/2 moles=3.173 X 10⁻³ moles of Al₂(SO₄)₃= 3.173 X 10⁻³ X 342 g of Al₂(SO₄)₃=1.085 g of Al₂(SO₄)₃.
So, mass percentage of Al₂(SO₄)₃ is= (amount of Al₂(SO₄)₃/total amount of mixture)X100 = 
=74.8 %.
