Answer:
P = 741.7 Pa
Explanation:
Pressure:
It is the force applied on object per unit area. The force is applied perpendicular to the surface.
Mathematical expression:
P = F/A
P = pressure
F = force
A = area
Given data:
Weight = 178 N
Area = 10 cm × 24 cm
Pressure = ?
Solution:
Area = 10 cm × 24 cm
Area = 240 cm²
Area = 240 /10000 = 0.024 m²
Formula:
P = F/A
P = 178 N / 0.024 m²
P = 741.7 Nm⁻²
Nm⁻² = Pa
P = 741.7 Pa
Answer: Event 1 is an example of a physical change and Event 2 is an example of a chemical change.
Explanation: Physical change is one in which there is no change in chemical composition of the substance. There is only a change in phase change.
Chemical change is a change in which there is a change in chemical composition and there might or might not be a phase change.
On Boiling, the water molecules remain bonded in the same form and only covert from liquid to gaseous form, thus is a physical change.
On Rusting of iron nail, the iron changes to iron oxide by combining with oxygen, there is a rearrangement of atoms and thus is a chemical change.

Protons : positive charge , about same mass as neutrons , in the nucleus
neutrons : no charge , about the same mass as a proton , in the nucleus
electrons : negative charge , less mass than protons and neutrons , in orbitals outside of the nucleus
Atoms is the correct answer
Explanation:
Defining law of definite proportions, it states that when two elements form more than one compound, the ratios of the masses of the second element which combine with a fixed mass of the first element will always be ratios of small whole numbers.
A. One of the oxides (Oxide 1) contains 63.2% of Mn.
Mass of the oxide = 100g
Mass of Mn = 63.2 g
Mass of O = 100 - 63.2
= 36.8 g
Ratio of Mn to O = 63.2/36.8
= 1.72
Another oxide (Oxide 2) contains 77.5% Mn.
Mass of oxide = 100 g
Mass of Mn = 77.5 g
Mass of O = 100 - 77.5
= 22.5 g
Ratio of Mn to O = 77.5/22.5
= 3.44
Therefore, the ratio of the masses of Mn and O in Oxide 1 and Oxide 2 is in the ratio 1.72 : 3.44, which is also 1 : 2. So the law of multiple proportions is obeyed.
B.
Oxide 1
Mass of Mn per 1 g of O = mass of Mn/mass of O
= 77.5/22.5
= 3.44 g/g of Oxygen.
Oxide 2
Mass of Mn per 1 g of O = mass of Mn/mass of O
= 77.5/22.5
= 3.44 g/g of Oxygen.