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tatyana61 [14]
2 years ago
10

A sample that weighs 107.75 g is a mixture of 30% helium atoms and 70% krypton atoms. How many particles are present in the samp

le?
Chemistry
1 answer:
r-ruslan [8.4K]2 years ago
5 0
<span>A sample that weighs 107.75 g is a mixture of 30% helium atoms and 70% krypton atoms. How many particles are present in the sample?    </span>3.59
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Which of the following statements concerning a metal crystallized in a face-centered cubic cell is/are CORRECT? 1. One metal ato
AleksAgata [21]

Answer:

Only 3 is correct.

Explanation:

The crystal of a metal or an ionic compound is called a cell, and there are 7 types of unit cells: cubic, tetragonal, orthorhombic, monoclinic, hexagonal, rhombohedral, and triclinic.

In a face-centered cubic cell (FCC) all angles are 90º and all lengths are equal. Each cubic cell has 8 atoms in each corner of the cube, and that atom is shared with 8 neighboring cells. So for a metal crystal, the atom is located at each of the eight lattice points, where it is shared equally between eight unit cells.

5 0
2 years ago
What volume of water must be added to 11.1 mL of a pH 2.0 solution of HNO3 in order to change the pH to 4.0? A) 11.1 mL B) 89 mL
Varvara68 [4.7K]

Answer:

Volume of water that must be added is 1.10 L

Explanation:

pH measures the acidity or the alkalinity of a substance

It is given by;

pH = -log[H+]

Using this we can find the concentration of H+ ions in the acid

pH = 2 = -log[H+]

Therefore;

[H+] = 10^-2

       = 0.01 M

But, since 1 mole HNO₃ ionizes to give 1 mole of H+, then the concentration of HNO₃ is equal to the concentration of H+ ([HNO₃] = [H+])

Therefore;

Initial [HNO₃] = 0.01 M

Initial volume of HNO₃ = 11.1 mL or 0.0111 L

We can then use dilution equation to find the final volume after dilution.

The final pH is 4

Therefore, [H+] = 10^-4

                         = 0.0001 M

Thus, the final concentration of HNO₃ is 0.0001 M

Using dilution equation;

M1V1 =M2V2

Thus; V2 = M1V1÷ M2

               = (0.01 M× 0.0111 L)÷ 0.0001 M

               = 1.11 L

This means the final total volume will 1.11 L or 1110 ml

Therefore; The volume of water added = 1110 ml - 11.1 ml

                                                                  = 1098.9 ml or

                                                                  = 1.0989 L

                                                                  = 1.10 L(2 d.p.)

Hence, The volume of water that must be added is 1.10 L

5 0
2 years ago
Which compound could serve as a reactant in a neutralization reaction ?
Veseljchak [2.6K]
 The   compound that  could serve  as  a reactant   in the neutralization reaction is    H2SO4
     
  Explanation
   Neutralization reaction occur  between an acids  and a base. H2SO4             (  sulfuric acid)  is  a strong  acid.  It can be neutralized by  strong base such as NaOH ( sodium  hydroxide)

  Example of neutralization reaction is

2NaOH + H2SO4 → Na2SO4  + 2H2O
7 0
2 years ago
How many moles are equal to 89.23 g of calcium oxide?
adelina 88 [10]
The molecular formula of calcium oxide - CaO
The molar mass of CaO - 40 + 16 = 56 g/mol 
Which means that 1 mol weighs 56 g
Therefore 56 g of CaO is - 1 mol
Then 89.23 g is equivalent to - 1/56 x 89.23 = 1.6 mol of CaO
0 0
2 years ago
Read 2 more answers
identify A and B, isomers of molecular formula C3H4Cl2, from the given 1H NMR data: Compound A exhibits peaks at 1.75 (doublet,
siniylev [52]

Answer:

See explaination

Explanation:

please kindly see attachment for the step by step solution of the given problem.

3 0
2 years ago
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