State which statement is a physical change or a chemical change: (a) Sawing wood
(b) Cooking eggs
(c) Melting chocolate
(d) Chewing sweets
(e) Rusting iron
(f) Filing your fingernails
(g) Milk turning sour
(h) Blow-drying your hair
(i) Boiling water
(j) Baking a cake
(k) Burning a match

Physical change: A,C ,D, F, H, I

Chemical Change: B, E, G, J, K

2.99 mol

Explanation:

Number of moles of CO₂ = ?

Volume = 67 L

Temperature and pressure = standard

Solution:

The given problem will be solve by using general gas equation,

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

By putting values,

1 atm × 67 L = n ×0.0821 atm.L/ mol.K × 273.15 K

67 atm.L = n×22.43 atm.L/ mol

n = 67 atm.L/22.43 atm.L/ mol

n = 2.99 mol