Give the number of protons, neutrons, and electrons in an atom of the^10Sr isoto

Question

Give the number of protons, neutrons, and electrons in an atom of the^10Sr isotope. 52 p, 38 n, 52 e 38 p, 90 n, 38 e 38 p, 38 n 38 e 38 p, 52 n, 38 e 90 p, 38 n, 90 e Calculate the molarity of a solution that contains 70.0 g of H_2SO_4 in 280. mL of solution 6.84 M 2.55 M 8.62 M 9.78 M 11.84 M Isotopes are atoms of the same element that have different nuclear charges. have different numbers of protons. have different atomic numbers. have different numbers of electrons. have different numbers of neutrons. How many grams of KOH are contained in 400. mL of 0.250 m KOH solution? 89.8 g 8.98 g 12.4 g 35.1 g 5.61 g Simple positively charged ions are always. than the neutral atoms from which they are formed. isoelectronic larger the same size smaller more anionic The number of can change without changing the element. electrons only neutron only protons only all of the above neutrons and electrons only is a noble gas. The number of electrons in a neutral atom of an element is always equal to the of the element. Avogadro's number isotope number mass number atomic number atomic mass unit A 10.0-L flask contains 0.400 mole of H_2, 0.300 mole of He and 0.500 mole of Ne at 35.0 degree C. What is the partial pressure of the Ne? 1.05 atm 0.144 atm 1.69 atm 1.26 atm 3.03 atm

Explanation / Answer

Dear Student,

9. Number of protons will be 38 because the element is Sr
The sum of the protons and neutrons give the isotope number. Here the isotope number is 90 and no. of protons is 38 so hence no. of neutrons will be 90 - 38 = 52
Number of electrons will be 38 because thats what required to have a neutral charge with 38 protons.

Therefore, option D = 38 p, 52 n, 38 e.

10. Given:

weight of H2SO4 = 70 g

To convert into moles = grams of H2SO4 / molar mass of H2SO4.

moles = 70 / 98.0785

This gives 0.7137 moles of H2SO4.

Volume of the solution = 280 ml = 280 / 1000 = 0.28 L

To find molarity of the solution.

Solution:

Molarity = moles of solute/ volume of solution in liters

Molarity of the solution = 0.7137 / 0.28

Molarity of the solution = 2.55 M

Therefore, option B = 2.55 M.

11. Isotopes are atoms of the same element that have different numbers of neutrons and therefore, different masses and different mass numbers (A) and different degrees of stability and different decay modes.

Therefore, option E = have different numbers of neutrons.

12. 1000 ml contains 0.250 moles

400 ml contains = (0.250/1000)*400 = 0.1 moles

molecular wt of KOH = 39 + 16 +1 = 56

so no of grams = 56*0.1 = 5.6 gms

Therefore. option E = 5.61 g.

13. Simply positively charged ions are always smaller than the neutral atoms from which they are formed.

Therefore, option D.

14. The number of neutrons and electrons only can change without changing the element.

Therefore, option E.

15. 36Kr is a noble gas.

The six noble gases that occur naturally are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn).

Therefore, option A.

16. The number of electrons in a neutral atom of every element is always equal to the atomic number of the element.

Therefore, option D.

17. Given:

0.4 moles of H2 , 0.3 moles of He and 0.5 moles of Ne

Hence, total moles of gas = 0.4 + 0.3 + 0.5 = 1.2 moles gas

Volume of the flask = 10 L

Temperature = 350 C = 273 + 35 = 308 K

To find partial pressure.

Solution:

Using Ideal Gas Law we get,

PV = nRT

P (10) = 1.2 x 0.0821 x 308

P = (1.2 x 0.0821 x 308 ) / 10

P = 30.34 / 10

P = 3.034 atm

Therefore, option E = 3.03 atm.

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