A model showing that gases are made from the matter of particles that are too small to see and are moving freely around in space can explain many observations.
Answer:
Option D. KBr < KCl < NaCl
Explanation:
We'll begin by calculating the number of mole of each sample.
This can be obtained as follow:
For NaCl:
Mass = 1 g
Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol
Mole of NaCl =?
Mole = mass /Molar mass
Mole of NaCl = 1/58.5
Mole of NaCl = 0.0171 mole
For Kbr:
Mass = 1 g
Molar mass of KBr = 39 + 80 = 119 g/mol
Mole of KBr =?
Mole = mass /Molar mass
Mole of KBr = 1/119
Mole of KBr = 0.0084 mole
For KCl:
Mass = 1 g
Molar mass of KCl = 39 + 35.5 = 74.5 g/mol
Mole of KCl =?
Mole = mass /Molar mass
Mole of KCl = 1/74.5
Mole of KCl = 0.0134 mole
Summary
Sample >>>>>>>> Number of mole
NaCl >>>>>>>>>> 0.0171
KBr >>>>>>>>>>> 0.0084
KCl >>>>>>>>>>> 0.0134
Arranging the number of mole of the sampl in increasing order, we have:
KBr < KCl < NaCl
The words aa q.s. is an abbreviation which is used in
pharmacy. This is usually written by prescribers and then translated by
pharmacists. The aa is derived from Latin which means “of each” while q.s. is
also derived from Latin which means “a sufficient quantity”. This simply means
that there is equal amount of Hytone 1% cream and Lotrimin 1% cream in the
total cream formulation.
Since we are to make a total of 60 g of cream, therefore
50% of it would be Lotrimin cream.
Amount of Lotrimin cream needed = 0.5 (60 g)
<span>Amount of Lotrimin cream needed = 30 grams</span>
Answer: Activation energy
Explanation:
In a chemical reaction, the reactants contains particles which must collide in order for a reaction to occur. The rate of reaction depends on the frequency of effective collision between the reacting particles. Effective collision are those that result in reactions, which when they occur the colliding particles become activated with increased kinetic energy.
This energy must exceed a particular energy barrier for a particular reaction if the reaction must take place. This energy barrier that must be overcome before a reaction takes place is known as the ACTIVATION ENERGY.
To explain further, when two particles or molecules A and B come in contact with each other, for a reaction to take place, they must collide with a sufficient force to break the bond that exists between them. The minimum combined kinetic energy these reactant particles must possess in order for their collision to result in a reaction is called the activation energy.
Option B: Strength of chemical bonds
Hardness defines the strength, it can not be compared with surface roughness as a smooth surface can be harder or difficult to break than a rough surface. The mass and weight of a substance matters while comparing density of substance or how heavy it is but it is not directly proportional to the hardness of the substance. Thus, equal masses of two substance can not be considered equally hard. Hardness depends on the inter-molecular interaction or forces within a substance, if the inter-molecular interactions are strong or the strength of chemical bonds is strong then the substance is more hard.
Therefore, hardness is directly proportional to strength of the chemical bonds.
