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lyudmila [28]
3 years ago
13

Which period is the shortest in the long form of the periodic table? Name all the

Chemistry
1 answer:
Andreyy893 years ago
8 0

Answer:

The first period is the shortest in the long form of periodic table

Explanation:

the long form or the modern periodic table is based on ht modern periodic law. it has 7 periods and 18 groups. this periodic table is widely used by people all over the world. the chemical and physical properties of the elements can be easily identified due to their classification into groups and periods or their position in the periodic table. the first period is the shortest in the long form of periodic table. there are two elements present, they are- hydrogen(H) and helium (He)

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Is a hollow tube that serves as passageway of air into the luns
KIM [24]

Answer:

The air that we breathe in enters the nose or mouth, flows through the throat (pharynx) and voice box (larynx) and enters the windpipe (trachea). The trachea divides into two hollow tubes called bronchi

Explanation:

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3 years ago
What is the expensive property of a substance
olya-2409 [2.1K]

is there any choices?

6 0
3 years ago
C3H8+3O2 = 3CO2+4H2O what is the enthalpy combustion
dezoksy [38]

Answer:

\Delta H_{comb}=2043.85kJ/mol

Explanation:

Hello there!

In this case, according to the given chemical reaction, it possible for us to set up the expression for the calculation of the enthalpy change as shown below:

\Delta H_r=-\Delta H_{comb}=3\Delta _fH_{CO_2}+4\Delta _fH_{H_2O}-\Delta _fH_{C_3H_8}-3\Delta _fH_{O_2}

Thus, given the values of the enthalpies of formation on the attached file, we obtain:-\Delta H_{comb}=3(-393.5kJ/mol)+4(-241.8kJ/mol)-(-103.85kJ/mol)-3(0kJ/mol)\\\\-\Delta H_{comb}=-2043.85kJ/mol\\\\\Delta H_{comb}=2043.85kJ/mol

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8 0
3 years ago
For an aqueous solution of hf, determine the van't hoff factor assuming 0% and 100% ionization, respectively. a solution is made
Snowcat [4.5K]
According to Osmotic pressure equation:

π = i M R T

When π =0.307 atm & M = 0.01 mol & R (constant)= 0.0821 L-atom/mol-K &
T= 22+273 = 295 Kelvin

So Van't half vector i = π / (MRT)
                                   = 0.307 / (0.01 * 0.0821 * 295)
                                   = 1.27 

When there is no dissociation, i = no. of moles of Hf in 1 L of solution = (1-X) 
and when there is a complete dissociation so it is equal 2X according to this equation


HF(aq) + H2O (L) ⇆ H3O (aq) + F (aq)
(1-X)                                X              X

∴ i = (1-X) + (2x)

 1.27 = 1+X
∴X= 1.27 - 1 = 0.27 
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7 0
3 years ago
Calculate the heat change involved when 2.00 L of water is heated from 20.0/C to 99.7/C in
IgorC [24]

Answer:

669.48 kJ

Explanation:

According to the question, we are required to determine the heat change involved.

We know that, heat change is given by the formula;

Heat change = Mass × change in temperature × Specific heat

In this case;

Change in temperature = Final temp - initial temp

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Specific heat of water is 4.2 J/g°C

Therefore;

Heat change = 2000 g × 79.7 °C × 4.2 J/g°C

                      = 669,480 joules

But, 1 kJ = 1000 J

Therefore, heat change is 669.48 kJ

7 0
3 years ago
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