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labwork [276]
3 years ago
10

How many elements have been discovered? A. 110 B. less than 110 C. more than 110

Chemistry
2 answers:
riadik2000 [5.3K]3 years ago
8 0
There are 115 known elements as of today (Feb. 13, 2016)

so, 'C' is the correct answer
Ivenika [448]3 years ago
6 0
C. more than 110. We have 115 elements known for Feb 2016.
You might be interested in
Arrange the sublevels in ascending order by the number of electrons they can contain. p sublevel s sublevel d sublevel f subleve
inn [45]

Electronic configuration of the atom describes  the arrangemnet of electrons in different shells and subshells ( sublevels).

Now , there are 4 types of sublevels: s, p , d and f . These sublevels have orbital which are spaces with high probability of having an electron and each orbital can have maximum 2 electrons.

Therefore,

s-sublevel has 1 orbital - it can have maximum 2 electrons.

p-sublevel has 3 orbitals - it can have maximum 6 electrons

d-sublevel has 5 orbitals - it can have maximum 10 electrons

f-sublevel has 7 orbitals - it can have maximum 14 electrons.

Hence, the acsending order of sublevels in terms of maximum number of electrons is:

<h2>s < p < d < f</h2>
3 0
3 years ago
Read 2 more answers
Write the formula for a compound of manganese (IV) hydroxide.?
Oxana [17]
You first add the manganese and exchange the number of electrons needed with the hydroxide. While the hydroxide needs only 1 electron the manganese needs 4, so after you exchange the electrons the manganese will be just 1 atom while the hydroxide is 4. Mn(OH)4
5 0
3 years ago
Using the following equation: 3H2SO4+ 2Fe -&gt; Fe2(SO4)3+ 3H2
Mariana [72]

Answer:

H₂SO₄

Explanation:

Given data:

Number of moles of H₂SO₄ = 15 mol

Number of moles of Fe = 13 mol

Which reactant is limiting reactant = ?

Solution:

Chemical equation:

3H₂SO₄  + 2Fe      →          Fe₂(SO₄)₃  + 3H₂

now we will compare the moles reactant with product.

               H₂SO₄         :          Fe₂(SO₄)₃  

                  3               :              1

                 15               :              1/3×15 = 5

                H₂SO₄         :            H₂

                  3               :              3

                 15               :              15

                Fe               :          Fe₂(SO₄)₃  

                  2               :              1

                 13               :              1/2×13 = 6.5

                Fe               :                H₂

                  2               :                 3

                 13               :              3/2×13 = 19.5

Number of moles of product formed by  H₂SO₄ are less thus it will act as limiting reactant.

8 0
3 years ago
The powder mixture (Cu, Al and Fe) = 10g was oxidized from sufficient chloride acid. 1) What are the possible reactions to the p
Mandarinka [93]

Answer:

1) 2Al + 6HCl ⟶ 2AlCl₃ + 3H₂

    Fe + 2HCl ⟶ FeCl₂ + H₂

2) Cu = 2.5 g; Al = 3.5 g; Fe = 4.0 g  

Explanation:

1) Possible reactions

2Al + 6HCl ⟶ 2AlCl₃ + 3H₂

Fe + 2HCl ⟶ FeCl₂ + H₂

2) Mass of each metal

a) Mass of Cu

The waste was the unreacted copper.

Mass of Cu = 2.5 g

b) Masses of Al and Fe

We have two relations :

Mass of Al + mass of Fe = 10 g - 2.5 g = 7.5 g

H₂ from Al + H₂ from Fe = 6.38 L at NTP

i) Calculate the moles of H₂

NTP is 20 °C and 1 atm.

\begin{array}{rcl}pV & = & n RT\\\text{1 atm} \times \text{6.38 L} & = & n \times 0.08206 \text{ L}\cdot\text{atm}\cdot\text{K}^{-1}\text{mol}^{-1} \times \text{293.15 K}\\6.38 & = & 24.06n \text{ mol}^{-1} \\n & = & \dfrac{6.38}{24.06 \text{ mol}^{-1} }\\\\ & = & \text{0.2652 mol}\\\end{array}

(ii) Solve the relationship

 Let x = mass of Al. Then

7.5 - x = mass of Fe

Moles of Al = x/27

Moles of Fe = (7.5 - x)/56

Moles of H₂ from Al = (3/2) × Moles of Al = (3/2) × (x/27) = x /18

Moles of H₂ from Fe = (1/1) × Moles of Fe = (7.5 - x)/56

∴ x/18 + (7.5 - x)/56 = 0.2652

    56x + 18(7.5 - x) = 267.3

      56x + 135 - 18x = 267.3

                        38x = 132.3

                            x = 3.5 g

Mass of Al = 3.5 g

Mass of Fe = 7.5 g - 3.5 g = 4.0 g

The masses of the metals are Cu = 2.5 g; Al = 3.5 g; Fe = 4.0 g

4 0
3 years ago
When calculating the equilibrium constant, aqueous solutes must be expressed in moles per liter (M), and gases must be expressed
alukav5142 [94]

Answer:

B. They are dimensionless ratios of the actual concentration or pressure divided by standard state concentration, which is 1 M for solutions and 1 bar for gases.

Explanation:

Activity of a substance is defined as the ratio of an effective concentration or an effective pressure to a standard state pressure or a standard state pressure. It is usually a unit less ratio.

Concentrations in an equilibrium constant are really dimensionless ratios of actual concentrations divided by standard state concentrations. Since standard states are 1 M for solutes, 1 bar for gases, and pure substances for solids and liquids, these are the units to be used.

Hence, activity is a fudge factor to ideal solutions that correct the true concentration. Activity of a gas and solute concentration is a ratio with no unit.

3 0
3 years ago
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