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Kryger [21]
3 years ago
5

HELPPPP ITS DUE TODAY

Chemistry
1 answer:
AnnZ [28]3 years ago
6 0

Answer:

Option C is correct : Calcium and magnesium are alkaline earth metals.

Explanation:

From the given option C is correct.

Calcium and magnesium are alkaline earth metals. Both are present in group 2. Each have 2 valence electrons.

All other options are incorrect, because:

a) Chlorine and iodine are alkali metals.

Chlorine and iodine are not alkali metals. These are halogens. Both have seven valence electrons and form salt with alkali metals.

B) Potassium and phosphorus are in the same group.

Potassium and phosphorus are not present in same groups. Potassium is present in group 1 and phosphorus is present in group 15.

d) Boron and silicon are present in same period.

Boron and silicon are not present in same period. Boron is present in period 2 while silicon is present in period 3.

e) Lead and tin both are non metals.

This option is also incorrect because lead and tin both are metals.

Thus, only option C is correct.

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Why is performing extraction with several small portions of a solvent more officient than a single extraction with the same tota
elena55 [62]

With various extractions the amount of material left in the trash will be lower, ergo the extraction will be more perfect. Various extractions with fewer amounts of solvent are more efficient than a single extraction with a huge amount of solvent.

<u>Explanation:</u>

Surely multiple extractions are better than the single large extraction. Because extraction is about maximizing outside field communication between the two solvents, and you easily get more surface area contact with fewer amounts.

You can merge two smaller portions quicker and more completely than with large portions.

6 0
3 years ago
What is a magnetic field
babymother [125]

a region around a magnetic material or a moving electric charge within which the force of magnetism acts.

5 0
3 years ago
A 0.652-g sample of a pure strontium halide reacts with excess sulfuric acid. the solid strontium sulfate formed is separated, d
seraphim [82]

Answer:

The formula of the original halide is SrCl₂.

Explanation:

  • The balanced equation of this reaction is:

SrX₂ + H₂SO₄ → SrSO₄ + 2 HX, where X is the halide.

  • From the equation stichiometry, 1.0 mole of strontium halide will result in 1.0 mole of SrSO₄.
  • The number of moles of SrSO₄ <em>(n = mass/molar mass) </em>= (0.755 g) / (183.68 g/mole) = 4.11 x 10⁻³ mole.
  • The number of moles of SrX are  4.11 x 10⁻³ moles from the stichiometry of the balanced equation.
  • n = mass / molar mass, n =  4.11 x 10⁻³ moles and mass = 0.652 g.
  • The molar mass of SrX₂ = mass / n = (0.652) / (4.11 x 10⁻³ moles) = 158.62 g/mole.
  • The molar mass of SrX₂ (158.62 g/mole) = Atomic mass of Sr (87.62 g/mole) + (2 x Atomic mass of halide X).
  • The atomic mass of halide X = (158.62 g/mole) - (87.62 g/mole) / 2 = 71 / 2  g/mole = 35.5 g/mole.
  • This is the atomic mass of Cl.
  • <em>So, the formula of the original halide is SrCl₂</em>.
4 0
3 years ago
What is the number of moles of solute in 250 mL of a 0.4 M solution?
mafiozo [28]

Answer:

0,1 mol

Explanation:

We know that the formula of concentration is C= moles of solute/ volume  

0,4 M= moles of solute/ 250 mL

Convert mL to L      250 mL =0,25 L

0,4 M x 0,25 L= moles of solute

0,1 moles= moles of solute

3 0
3 years ago
How many grams of O2 are needed to react with 18.2 g of NH3?
erastova [34]

Answer:

44 g oxygen are needed.

Explanation:

Given data:

Mass of oxygen needed = ?

Mass of ammonia = 18.2 g

Solution:

Chemical equation:

4NH₃ + 5O₂   →  4NO + 6H₂O

Now we will calculate the number of moles of ammonia:

Number of moles = mass/molar mass

Number of moles = 18.2 g/ 17 g/mol

Number of moles = 1.1 mol

Now we will compare the moles of ammonia with oxygen from balance chemical equation.

                        NH₃              :                O₂

                          4                 :                 5

                          1.1                :              5/4×1.1 = 1.375 mol

Mass of oxygen needed:

Mass = number of moles × molar mass

Mass = 1.375 mol × 32 g/mol

Mass = 44 g

4 0
3 years ago
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