Answer:
Option-D : <span>Decrease the velocities of the particles, and decrease the space between the particles.
Explanation:
The solid state of matter is composed of particles closely packed with a minimum space between them. This closed packing of particles occur due to strong interatomic or intermolecular interactions between particles. Therefore, solids particles have zero translational and rotational motions and only show vibrational motions. So, decrease in velocity and decrease in space between particles is the right answer for making solids.</span>
Answer:
(d) burning a log.
(b) toasting a slice of bread;
Explanation:
Chemical change -
A chemical change refers to , the change in which a new compound is formed .
From the question ,
Its is not a chemical process , since no new compound is formed , these is only change in state as the liquid is turning to gaseous sate .
It is not a chemical process , as no new substance is formed .
- toasting a slice of bread
It is a chemical change , in which bread surface is deposited by a brown coat via the process of heating , even this process is a irreversible in nature .
It is a chemical change , as with the help of heating , the wood is turning to ashes .
Answer: 4.21×10⁻⁸
Explanation:
1) Assume a general equation for the ionization of the weak acid:
Let HA be the weak acid, then the ionization equation is:
HA ⇄ H⁺ + A⁻
2) Then, the expression for the ionization constant is:
Ka = [H⁺][A⁻] / [HA]
There, [H⁺] = [A⁻], and [HA] = 0.150 M (data given)
3) So, you need to determine [H⁺] which you do from the pH.
By definition, pH = - log [H⁺]
And from the data given pH = 4.1
⇒ 4.10 = - log [H⁺] ⇒ [H⁺] = antilog (- 4.10) = 7.94×10⁻⁵
4) Now you have all the values to calculate the expression for Ka:
ka = 7.94×10⁻⁵ × 7.94×10⁻⁵ / 0.150 = 4.21×10⁻⁸
Answer:
Mass = 279.23 g
Explanation:
Given data:
Number of moles of Fe₂O₃ = 3 mol
Number of moles of Al = 5 mol
Maximum amount of iron produced by reaction = ?
Solution:
Chemical equation:
Fe₂O₃ + 2Al → Al₂O₃ + 2Fe
Now we will compare the moles of iron with Al and iron oxide.
Fe₂O₃ : Fe
1 : 2
3 : 2×3 = 6 mol
Al : Fe
2 : 2
5 : 5 mol
The number of moles of iron produced by Al are less so Al is limiting reacting and it will limit the amount of iron so maximum number of iron produced are 5 moles.
Mass of iron:
Mass = number of moles × molar mass
Mass = 5 mol × 55.845 g/mol
Mass = 279.23 g
