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Andreas93 [3]
2 years ago
14

What are groups on the periodic table? How many are there?

Chemistry
2 answers:
Amiraneli [1.4K]2 years ago
6 0

Explanation:

Groups are numbered 1–18 from left to right. The elements in group 1 are known as the alkali metals; those in group 2 are the alkaline earth metals; those in 15 are the pnictogens; those in 16 are the chalcogens; those in 17 are the halogens; and those in 18 are the noble gases.

s344n2d4d5 [400]2 years ago
5 0

Answer:

The s-, p-, and d-block elements of the periodic table are arranged into 18 numbered columns, or groups.

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2. Worm Y reproduces sexually, which gives it genetic variation.

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How many molecules are in 6.0g of sodium phosphate?
Phantasy [73]

Answer:

2.2 x 10²² molecules.

Explanation:

  • Firstly, we need to calculate the no. of moles in (6.0 g) sodium phosphate:

<em>no. of moles = mass/molar mass </em>= (6.0 g)/(163.94 g/mol) = <em>0.0366 mol.</em>

  • <em>It is known that every mole of a molecule contains Avogadro's number (6.022 x 10²³) of molecules.</em>

<em />

<u><em>using cross multiplication:</em></u>

1.0 mole of sodium phosphate contains → 6.022 x 10²³ molecules.

0.0366 mole of sodium phosphate contains → ??? molecules.

<em>∴ The no. of molecules in  6.0 g of sodium phosphate</em> = (6.022 x 10²³ molecules)(0.0366 mole)/(1.0 mole) = <em>2.2 x 10²² molecules.</em>

3 0
2 years ago
Water has a slight negative charge around its oxygen atom, and a slight positive charge around its hydrogen atoms Which type of
allochka39001 [22]
C.
Water is polar because one side of the molecule is positive and the other is negative.
3 0
3 years ago
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The complete combustion of propane (C3H8) in the presence of oxygen yields CO2 and H2O: C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (g) a
mixas84 [53]

Answer:

26.9 L is the volume of CO₂, we obtained

Explanation:

The reaction is: C₃H₈(g) + 5O₂(g)  →  3CO₂ (g) + 4H₂O (g)

Let's determine the reactants moles:

27.5 g . 1mol / 44 g = 0.625 moles

We need density of O₂ to determine mass and then, the moles.

O₂ density = O₂ mass / O₂ volume

O₂ density . O₂ volume = O₂ mass

1.429 g/L . 45L = O₂ mass → 64.3 g

Moles of O₂ → 64.3 g . 1mol/32g = 2.009 moles

Let's find out the limiting reactant:

1 mol of propane needs 5 moles of oxygen to react

Then, 0.625 moles will react with (0.625 . 5)/1 = 3.125 moles of O₂

Oxygen is the limiting reactant, we need 3.125 moles but we only have 2.009 moles

Ratio is 5:3. 5 moles of O₂ produce 3 moles of CO₂

Therefore, 2.009 moles of O₂ must produce (2.009 .3) /5 = 1.21 moles of CO₂. Let's find out the volume, by Ideal Gases Law (STP are 1 atm and 273K, the standard conditions)

1 atm . V = 1.21 moles . 0.082 . 273K

V = (1.21 moles . 0.082 . 273K) / 1atm = 26.9 L

3 0
3 years ago
A train in Japan can travel 813.5 miles in 5 hours
Anastaziya [24]

Answer:

162.7miles/hr

Explanation:

Given parameters:

Distance covered by the train  = 813.5miles

Time taken  = 5hours

Unknown:

Speed of the train  = ?

Solution:

Speed is a physical quantity.

It is mathematically expressed as;

      Speed  = \frac{distance}{time}

So, input parameters and solve;

   Speed  = \frac{813.5}{5}  = 162.7miles/hr

8 0
3 years ago
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