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Ainat [17]
3 years ago
9

Which of these is an isoelectronic series? question 7 options: 1) na+, k+, rb+, cs+ 2) k+, ca2+, ar, s2– 3) na+, mg2+, s2–, cl–

4) li, be, b, c 5) none of these (a-d) save?
Chemistry
1 answer:
-BARSIC- [3]3 years ago
6 0
An isoelectronic series is where all of the ions listed have the same number of electrons in their atoms. When an atom has net charge of zero or neutral, it has equal number of protons and electrons. Hence, it means that the atomic number = no. of protons = no. of electrons. If these atoms become ions, they gain a net charge of + or -. Positive ions are cations. This means that they readily GIVE UP electrons, whereas negative ions (anions) readily ACCEPT electrons. So, to know which of these are isoelectronic, let's establish first the number of electron in a neutral atom from the periodic table:

Na=11; K=19; Rb=37; Cs = 55; Ca=20; S=16; Mg=12; Li=3; Be=4; B=5; C=6, Ar = 18

A. Na⁺: 11-1 = 10 electrons
     K⁺: 19 - 1 = 18 electrons
     Rb⁺: 37-1 = 36 electrons

B. K⁺: 19 - 1 = 18 electrons
    Ca²⁺: 20 - 2 = 18 electrons
    Ar:  18 electrons
    S²⁻:  16 +2 = 18 electrons

C. Na⁺: 11-1 = 10 electrons
    Mg²⁺: 12 - 2 = 10 electrons
     S²⁻:  16 +2 = 18 electrons

D. Li=3 electrons
    Be=4 electrons
    B=5 electrons
    C=6 electrons

The answer is letter B.
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Answer: -105 kJ

Explanation:-

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N_2(g)+3H_2(g)\rightarrow 2NH_3(g)

The expression for enthalpy change is,

\Delta H=\sum [n\times B.E(reactant)]-\sum [n\times B.E(product)]

\Delta H=[(n_{N_2}\times B.E_{N_2})+(n_{H_2}\times B.E_{H_2}) ]-[(n_{NH_3}\times B.E_{NH_3})]

\Delta H=[(n_{N_2}\times B.E_{N\equiv N})+(n_{H_2}\times B.E_{H-H}) ]-[(n_{NH_3}\times 3\times B.E_{N-H})]

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n = number of moles

Now put all the given values in this expression, we get

\Delta H=[(1\times 945)+(3\times 432)]-[(2\times 3\times 391)]

Delta H=-105kJ

Therefore, the enthalpy change for this reaction is, -105 kJ

8 0
3 years ago
Sodium (Na) and potassium (K) are in the same group in the periodic table. Sodium is in the 11th position. How many valence elec
lapo4ka [179]
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8 0
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6. Calculate the molarity if 35.0 grams of KBr are dissolved in 700. ml?
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Answer:

To calculate molarity, divide the number of moles of solute by the volume of the solution in liters. If you don't know the number of moles of solute but you know the mass, start by finding the molar mass of the solute, which is equal to all of the molar masses of each element in the solution added together.

Explanation:

try starting with 35.0 and dived it by the volume

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Thus we can conclude that Fe₂P causes decrease in yield

Learn more about production of phosphorus at brainly.com/question/13337198

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6 0
2 years ago
How many joules are required to heat 2 l of water in a pot from 20 ◦c to the boiling point of water? the specific heat of water
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M  =     1g/ml  x2000  ml  =  2000g
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Q  is therefore  =   2000 g x 4.18 j/g c  x  80c  =  668800j
 


4 0
3 years ago
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