Answer:
<u>The incorrect choice is the last one:</u>
- <em>In the Leucipo and Democritus atomic model, electrons had negative charges.</em>
Explanation:
The translation of the question is:
Choose the incorrect statement. *
- Matter is everything that has mass and occupies volume.
- Mass and weight are different quantities. Mass is a measure of how much matter an object has, and weight is a measure of the gravitational pull force suffered by the object.
- Dalton's atomic model has similarities to the atomic model described by Leucipo and Democritus.
- Dalton thought that atoms of the same element could not combine, as they developed mutual repulsion.
- In the Leucipo and Democritus atomic model, electrons had negative charges.
<h2>Solution</h2>
The <em>last statement is false</em> because Leucipo and Democritus thought that the atom was an indivisible particle. This is, they did not think there were subatomic particles, such as electrons. Furthermore, the idea of a particle with a negative charge was developed much time (centuries) later.
As for the other statements:
- <em>Matter is everything that has mass and occupies volume</em>: this is the current definition of matter; for instance, wood, air, atoms, have mass and occupy volume. Thougths, feelings do not have either mass or occupy a volume, they are not matter.
- <em>Mass and weight are different quantities</em>. <em>Mass is a measure of how much matter an object has, and weight is a measure of the gravitational pull force suffered by the object</em>. Indeed, the mass is determined by the number of atoms of the substance, but weight is the force of attraction from Earth (or other planet, if the object is in other planet). Mass does not change with the location; weight does.
- <em>Dalton's atomic model has similarities to the atomic model described by Leucipo and Democritus</em>: sure. This is a hystorical question. Leucippus and Democritus were two Greek phylosophers who believed that the matter was formed by tiny solid particles, the atom.
- <em>Dalton thought that atoms of the same element could not combine, as they developed mutual repulsion</em>. In the times of Dalton, when he developed the law of multiple proportions, atoms of a same kind were thought to repel each other.
P1V1=4P1V2
V2/V1= P1/4P1
V2/V1= 1/4
V2=1/4*V1
volume will decrease by factor 1/4
Since the number of moles of a substance is the mass divided by the molar mass of the substance, we can just simply multiply the molar mass of magnesium chloride by the number of moles, which is 4.40 in this case.
To find the molar mass, refer to the periodic table for the relative atomic mass of Mg and Cl and add them together. Since there’s 2 chloride ions in MgCl2, double the relative atomic mass of Cl when adding.
24.31 + 35.45x2
=95.21
Now just multiply 95.21 to 4.40mol, which you’ll get 418.9g (corrected to 3 significant figures)
C. Weak acids partially ionize
Answer:
0.112 M.
Explanation:
- Molarity is the no. of moles of solute in a 1.0 L of the solution.
M = n/V.
<em>M = (mass/molar mass)solute x (1000/V of the solution).</em>
mass = 127.62 g.
molar mass = 286.138 g/mol.
V of the solution = 4.0 L = 4000.0 mL.
<em>∴ M = (mass/molar mass)solute x (1000/V of the solution)</em> = (127.62 g / 286.138 g/mol) x (1000 / 4000.0 mL) = <em>0.1115 M ≅ 0.112 M.</em>
