Answer: Option (C) is the correct answer.
Explanation:
When chemical composition of a substance is not changing in a chemical reaction then it is known as a physical change.
For example, when water change state, from ice to steam then it means solid state is changing into gaseous state.
Therefore, it is a physical change.
And, a reaction which causes change in chemical composition is known as a chemical change.
For example, 
Thus, we can conclude that we can see water change state, from ice to steam. This is a physical change in matter.
Answer: iron (oxides of iron)
Explanation: manganese nodules usually contain layers of iron and manganese oxides in a concentric arrangement and are called polymetallic nodules.
Answer:
Part A = The mass of sulfur is 6.228 grams
Part B = The mass of 1 silver atom is 1.79 * 10^-22 grams
Explanation:
Part A
Step 1: Data given
A mixture of carbon and sulfur has a mass of 9.0 g
Mass of the product = 27.1 grams
X = mass carbon
Y = mass sulfur
x + y = 9.0 grams
x = 9.0 - y
x(molar mass CO2/atomic mass C) + y(molar mass SO2/atomic mass S) = 22.6
(9 - y)*(44.01/12.01) + y(64.07/32.07)
(9-y)(3.664) + y(1.998)
32.976 - 3.664y + 1.998y = 22.6
-1.666y = -10.376
y = 6.228 = mass sulfur
x = 9.0 - 6.228 = 2.772 grams = mass C
The mass of sulfur is 6.228 grams
Part B
Calculate the mass, in grams, of a single silver atom (mAg = 107.87 amu ).
Calculate moles of 1 silver atom
Moles = 1/ 6.022*10^23
Moles = 1.66*10^-24 moles
Mass = moles * molar mass
Mass = 1.66*10 ^-24 moles *107.87
Mass = 1.79 * 10^-22 grams
The mass of 1 silver atom is 1.79 * 10^-22 grams
Answer : The correct option is, pressure.
Explanation :
The ideal gas equation is,

where,
P = pressure of the gas
V = volume of the gas
n = number of moles of gas
T = temperature of the gas
R = gas constant
The value of 'R' has several different values which are :




That means, the value of 'R' is different due the change in the pressure value and all the variables (temperature, volume and moles) are constant.
Hence, the correct option is, pressure.