The reaction is given as
Fe2O3 (s)+ 3CO(g)--->3CO2(g)+ 2Fe(s)
No.of moles=mass in gram/molar mass
As for Fe mole =156.2g/55.847=2.7969~2.797
The ratio b/w CO and Fe is 3:2
Moles of CO needed= 2.797x3/2=4.1955
Mass of CO needed= 4.195mol x 28.01g/mol= 117.515g
Complete Question
A sample of aluminum, which has a specific heat capacity of 0.897 JB loc ! is put into a calorimeter (see sketch at right) that contains 200.0 g of water. The aluminum sample starts off at 85.6 °C and the temperature of the water starts off at 16.0 °C. When the temperature of the water stops changing it's 20.1 °C. The pressure remains constant at 1 atm. Calculate the mass of the aluminum sample.
Answer:

Explanation:
From the question we are told that:
Heat Capacity 
Mass of water 
Initial Temperature of Aluminium 
Initial Temperature of Water 
Final Temperature of Water 
Generally
Heat loss=Heat Gain
Therefore


Answer: a.KOH
Potassium hydroxide is an ionic compound where the K+ is the cation and OH−is the anion. At the same time, the compound also contains a covalent bond since the anion, OH−is formed from electron sharing between the O and H atoms.
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Explanation:
Answer:
Mass = 90.28 g
Explanation:
Given data:
Mass of Ca(OH)₂ = ?
Volume of solution= 1.5 L
Molarity of solution = 0.81 M
Solution:
First of all we will calculate number of moles.
Molarity = number of moles / volume in L
by putting values,
0.81 M = Number of moles / 1.5 L
Number of moles = 0.81 M × 1.5 L
Number of moles = 1.22 mol
Mass of Ca(OH)₂ in gram:
Mass = number of moles × molar mass
Mass = 1.22 mol × 74.09 g/mol
Mass = 90.28 g