[jenny]

I am a senior attending online courses to complete highschool. I can't seem to teach myself chemistry and need someone to explain to me how to work these problems out.


(1)Which chemical formula is incorrect?
 
  a. MgCO3
  b. Fe(C2H3O 2)3
  c. NH4SO4
  d. Al(NO3)3
 
(2)What is the correct formula of a base?
 
  a. Al(OH)2
  b. Na(OH)2
  c. CO2
  d. Ca(OH)2

(3)When magnesium metal (Z = 12) burns, it forms magnesium oxide (MgO). If 25.0 grams of MgO are produced, how many grams of Mg would be found in the compound?
 
  a. 24.0 grams
  b. 0.96 grams
  c. 15.0 grams
  d. 10.0 grams
 
(4)Suppose lead (Z = 82) forms two compounds with sulfur (Z = 16). In one compound, 0.76 grams of lead combines with 1.00 grams of sulfur. According to the law of multiple proportions, what amount of lead is NOT capable of forming another compound with 1.00 grams of sulfur?
 
  a. 0.42 grams
  b. 1.52 grams
  c. 0.38 grams
  d. 2.28 grams
 
(5)Diamonds are made of carbon atoms connected in a molecular solid. Which diamond would have the greatest mass?
 
  a. a one-carat diamond
  b. a diamond that contained 0.0010 moles of carbon
  c. a diamond that contained 6.02 x 1021 atoms of carbon
  d. a diamond with a mass of 250 mg
 
(6)Right now, calcium (Z = 20) ions are moving through your cells. How many moles are represented by 0.00020 grams of Ca2+?
 
  a. 1.2 x 1020 moles
  b. 1.0 x 10–5 moles
  c. 5.0 x 10–6 moles
  d. 2.0 x 105 moles
 
(7)One ounce of gold (Z = 79) has a mass of approximately 28 grams. How many atoms would be in one ounce of gold?
 
  a. 8.6 x 1022 atoms
  b. 197 atoms
  c. 6.02 x 1023 atoms
  d. 4.2 x 1020 atoms

(8)Which compound contains the greatest mass per mole?
 
  a. CO2
  b. NaCl
  c. C2H5O
  d. C3H8
 
(9)Which of the following contains the greatest number of molecules?
 
  a. 1.5 x 1020 molecules of NH3
  b. 0.0050 moles of NH3
  c. 1.00 grams of NH3
  d. a sample of NH3 with a total of 6.0 x 1020 atoms of N and H
 
(10)Which expression indicates the greatest number of representative particles?
 
  a. 6.02 x 1023 ions of Fe3+
  b. 6.02 x 1023 molecules of CO2
  c. 6.02 x 1023 representative units of CaCO3
  d. All are the same
 

[opti384]

You got to show your attempts first 

[DevaDevil]

Indeed, show your attempts first, but I will give some small hints that can get you going.

Questions 1&2: which are the basic ions each compound is made up from, including their formal charges?

Q 3&4; write the reaction equations first, then start reasoning.

Q 5&9: convert each unit of measure in grams (Q5, all are pure carbon) or molecules (Q9) using molar mass and Avogadro's number, you should be able to do that!

Q 6-8: molar mass? You should know what that is, and how to apply it.

Q 10: using the definition of "representative particle", reason which answer is correct.

[AMEDIO]

show where are u stuck??

[Vidya]

Try Q1 and Q2
Use periodic table to answer the question and polyatomic ions table to answer the questions