Each molecule contains 3 oxygen atoms GFM 50g CaCO3 1 mole CaCO3 3 mole O 6.022 x 1023 atoms O 100g CaCO3 1 mole CaCO3 1 mole O View whole question: Each row contains same substance CaCO3 looks like all is about moles so GFM is key Look at answer choices make a conclusion choose which is key Here I see if statement II is true only two answer choices are possible so I will check this first Annotate statement 2 Find GFM of CaCO3 = 100 Strategy independently assess each one Therefore each row needs its own annotation

goal Given 200g CaCO3 1 mole CaCO3 100g CaCO3 Since 2 is true then all I need to do is check if III is true

Enough CH4 to make 2 moles of CO2 1 2 1 2 32g CH4 1 mole CH4 1 mole CO2 2 mole CO2 16g CH4 1 mole CH4 View whole question Look like I need to balance this first 32g O2 1 mole O2 1 mole CO2 Only ½ mole of CO2 is made Enough CH4 to make 2 moles of CO2 Therefore enough CH4 left to make 1.5 mole of CO2 1/2 mole CO2 32g O2 2 mole O2

RATIO !! View whole question This question is about ratios So don’t get put off by the complexity of the equation Just know the sorry 1A reacts with 5B and 8C to make 1D, 5E and 4F

Given Given 6 mole C3H8 4 mole HCl goal 24 mole HCl 1 mole C3H8 Two givens and 1 goal this normally means a limiting reactant question 20 mole Cl2 4 mole HCl Two “Given”s one Goal LIMITING!?! 20 mole HCl 4 mole Cl2

So 1.5 x 10 23 atoms have a mass of 12 g Mass of one mole 6.022 x 1023 = one mole So 1.5 x 10 23 atoms have a mass of 12 g So 6.022 x 10 23 would have a mass of This is a ratio question 12g is to 1.5 x 1023 as gfm is to 6.022 x 1023 So 1.5 x 10 23 atoms is to 12 g as 6.022 x 10 23 is to GFM

Cross multiply and solve 72.26g = 1.5 GFM g Mass of one mole 12g GFM g 6.022 x 1023 = one mole = 1.5 x 1023 6.022 x 1023 Multiply both sides by 1023 12g GFM g = This is a ratio question 12g is to 1.5 x 1023 as gfm is to 6.022 x 1023 1.5 6.022 Cross multiply and solve 72.26g = 1.5 GFM g 48.2g

Each molecule contains 3 oxygen atoms ¼ of a mole ¼ of a mole Each molecule contains 3 oxygen atoms This is a ratio question 12g is to 1.5 x 1023 as gfm is to 6.022 x 1023