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julia-pushkina [17]
2 years ago
12

How many Groups is the modern periodic table divided into? A. 2 B. 3 C. 7 D. 18

Chemistry
2 answers:
RSB [31]2 years ago
4 0
18

In chemistry, a group is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table; the f-block columns are not numbered.
velikii [3]2 years ago
3 0

Answer:

18.

Explanation:

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Radiation with a wavelength of 4.2nm
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The answer is X Ray

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6 0
3 years ago
NItrogen in air reacts at high temperature to form NO2 according to the reaction:
Rina8888 [55]

Answer:

The correct answer is option E.

Explanation:

Structures for the reactants and products are given in an aimage ;

Number of double bonds in oxygen gas molecule = 1

Number of double bonds in nitro dioxide gas molecule = 1

Number of single bond in in nitro dioxide gas molecule = 1

Number of triple bonds in nitrogen gas molecule = 1

N_2+2O_2\rightarrow 2NO_2,\Delta H=?

\Delta H=[2 mol\times \Delta H_{f,NO_2}]-[1 mol\times \Delta H_{f,N_2}-2 mol\times \Delta H_{f,O_2}]

\Delta H_{f,NO_2}=33.18 kJ/mol

\Delta H_{f,N_2}=0 (pure element)

\Delta H_{f,O_2}=0 (pure element )

\Delta H=2 mol\times 33.18 kJ/mol=66.36kJ=15.86 kcal

The enthalpy of the given reaction is 15.86 kcal.

6 0
3 years ago
For the equilibrium PCl5(g) PCl3(g) + Cl2(g), Kc = 2.0 × 101 at 240°C. If pure PCl5 is placed in a 1.00-L container and allowed
Cloud [144]

Answer:

the equilibrium concentration of [PCl₅] is 3.64*10⁻³ M

Explanation:

for the reaction

PCl₅(g) → PCl₃(g) + Cl₂(g)

where

Kc= [PCl₃]*[Cl₂]/[PCl₅] = 2.0*10¹ M = 20 M

and [A] denote concentrations of A

if initially the mixture is pure PCl₅ , then it will dissociate according to the reaction and since always one mole of PCl₃(g) is generated with one mole of Cl₂(g) , the total number of moles of both at the end is the same → they have the same concentration → [PCl₃(g)] = [Cl₂]=0.27 M

therefore

Kc= [PCl₃]*[Cl₂]/[PCl₅] = 0.27 M* 0.27 M /[PCl₅] = 20 M

[PCl₅]  =  0.27 M* 0.27 M / 20 M = 3.64*10⁻³ M

[PCl₅]  = 3.64*10⁻³ M

the equilibrium concentration of [PCl₅] is 3.64*10⁻³ M

6 0
3 years ago
With the help of balanced chemical equation explain what happens when:(1)Zinc is put in dilute hydrochloric acid (2)Zinc is put
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