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4 years ago

Which of the following statements is true about the periodic table.

Chemistry

2 answers:

mixer [17]4 years ago

8 0

Answer:

In this question, the statement 2 is correct and true while other statements are incorrect.

Explanation:

The properties of an element can be easily predicted from the periodic table. We can find out the atomic number of the element from the periodic table. According to the periodic table, the properties of element is dependent on the atomic number of the element. The behavior of element during a chemical reaction can be predicted from the atomic number.

Element can only belong to one group at a time. Hence, statement (3) is not correct.

The periodic table is still used by scientists for predicting the properties. Hence, it is not outdated. Statement (1) is not correct.

Statement (2) is correct

kodGreya [7K]4 years ago

5 0

Answer: 2

Explanation:

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What is the oxidation number of Gallium?

love history [14]

Answer:

Explanation:

Sorry, I don't have one for now. I remember answering this a while ago, but I don't remember the exact reason why it's 3+.

5 0

4 years ago

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At 20 ?C the vapor pressure of benzene (C6H6)is 75 torr, and that of toluene (C7H8) is 22 torr

tia_tia [17]

Answer:

(a) Benzene = 0.26; toluene = 0.74

(b) Benzene = 0.55

Explanation:

1. Calculate the composition of the solution

For convenience, let’s call benzene Component 1 and toluene Component 2.

According to Raoult’s Law,

$p_{1} = \chi_{1}p_{1}^{\circ}\\p_{2} = \chi_{2}p_{2}^{\circ}$

where

p₁ and p₂ are the vapour pressures of the components above the solution

χ₁ and χ₂ are the mole fractions of the components

p₁° and p₂° are the vapour pressures of the pure components.

Note that

χ₁ + χ₂ = 1

So,

$\begin{array}{rcl}p_{\text{tot}} &=& p_{1} + p_{2}\\p_{\text{tot}} & = & \chi_{1}p_{1}^{\circ} + (1 - \chi_{1})p_{2}^{\circ}\\36 & = & \chi_{1}\times 75 + (1 - \chi_{1}) \times 22 \\36 & = & 75\chi_{1} + 22 -22\chi_{1}\\14 & = & 53\chi_{1}\\\chi_{1} & = & \mathbf{0.26}\\\end{array}$

χ₁ = 0.26 and χ₂ = 0.74

2. Calculate the mole fraction of benzene in the vapour

In the liquid,

p₁ = χ₁p₁° = 0.26 × 75 mm = 20 mm

∴ In the vapour

$\chi_{1} = \dfrac{p_{1}}{p_{\text{tot}} } = \dfrac{\text{20 mm} }{\text{36 mm}} = 0.55$

Note that the vapour composition diagram below has toluene along the horizontal axis. The purple line is the vapour pressure curve for the vapour. Since χ₂ has dropped to 0.45, χ₁ has increased to 0.55.

7 0

3 years ago

Sodium is a larger atom than lithium. List three reasons why this is true.

just olya [345]

Answer:

It is present in third period that's why its valance electrons are present in 3rd energy level.

Its atomic number is greater than lithium when compared in group wise.

There are more electrons in sodium to shield the outer valance electron thus nuclear attraction becomes weak and size increase.

Explanation:

The size of sodium is greater than lithium because atomic number of sodium is 11 and lithium is 3. Both are present in first group but sodium is present down to the lithium. As we move from top to bottom in a group atomic size increases with addition of electrons. The nuclear effect become weaker on valance electrons and atomic size increase. Same time shielding effect is also produces which shield the outer electrons from the influence of nucleus. While in case of lithium less electrons are present to shield the valance electrons.

As we note the position of both elements along period. The sodium is present in third period while lithium is present in second period. So, in case of sodium third energy level is involved. That's why its size is greater than lithium.

8 0

3 years ago

1. A balloon contains 100g of oxygen gas (O₂) when the volume is 110 dm³. Find the volume of the balloon when the mass of oxygen

igor_vitrenko [27]

The volume of the balloon when the mass of oxygen gas is decreased to 50g is 50L.

We will use the ideal gas equation-

P=Pressure

V=volume

n=no. of moles

T=temperature

In this question temperature and pressure will remains constant then the above equation can be rewritten as-

$V_{1} /n_{1} =V_{2} /n2$

where V1= initial volume of the balloon

V2= volume of the balloon when the mass of oxygen gas is decreased to 50g

now, substitute the values in the above equation-

V1=100dm3=100L

n1=100/32=3.12

n2=50/32=1.56

100/3.12=V2/1.56

V2=50 L

hence, the volume of the balloon when the mass of oxygen gas is decreased to 50g is 50L.

learn more about the ideal gas equation here:

brainly.com/question/1056445

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2 years ago

How would you describe the change in the arrangement of particles as heat energy and temperature increase?

snow_tiger [21]

Since there is more energy added as heat rises, the particles disperse and have larger movements.

6 0

3 years ago

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