CHEMISTRY MIDDLE SCHOOL

Which notations represent different isotopes of the element sodium?(1) 32S and 34S (3) Na+ and Nao
(2) S2- and S6+ (4) 22Na and 23Na

Answers

Answer 1
Answer: The notations representing the different isotopes of the element sodium are:

4) 22Na and 23Na

The total number of recognized isotopes of sodium is 20. It starts from 18Na upto 37Na with two isomers (22mNa and 24mNa).

23Na is considered as monoisotopic element meaning it has a single stable isotope making it primordial isotope. 23Na is a single isotope since earth was formed. It has a standard atomic mass of 22.989 769 28(2) u.

22Na, a positron-emitting isotope with a long half life = 2.605 years. It is used to create test objects and point sources for PET or positron emission tomography.

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Which element would most likely have a chemical reactivity similar to bromine?A) Chlorine

B) Sulfur

C) Selenium

D) Phosphorus

Plz hurry up!!

Answers

Answer:

I would say C)Selenium because it has a closer amount of valence electrons in the atom but I could be wrong as well no one is perfect. If that's not the answer then ask for some help by the teacher it's likely that you'll get the most help there

Brandy knows that chromosomes behave differently in meiosis and mitosis what do chromosomes do in meiosis but not in mitosis

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Meiosis has two rounds of genetic and cellular division while Mitosis only has one. There are more complicated answers, so i dont know exactly how much info you need.

Name two landforms created from deposits by rivers.

Answers

Alluvial fans and deltas are formed.

Which of the following changes would show a decrease in kinetic energy​

Answers

Answer:

Kinetic energy is the energy of movement or change. Potential energy is the energy a system has as a result of being able to undergo some change. ... As an object falls its potential energy decreases, while its kinetic energy increases. The decrease in potential energy is exactly equal to the increase in kinetic energy.

Calculate the mass of barium sulphate formed when 500 cm3 of 1 mol dm sodium sulphate solution is reacted completely with barium chloride solution.[ Relative atomic mass : O = 16; S = 32; Ba = 1371​

Answers

Answer:

116.69 g.

Explanation:

Let's write down the reaction taking place when barium chloride reacts with sodium sulfate. This is a double displacement reaction, meaning the anions will be exchanged to produce barium sulfate and sodium chloride:

BaCl_2(aq)+Na_2SO_4(aq)\rightarrow BaSO_4(s)+2 NaCl(aq)

Let's find the moles of sodium sulfate. Given the volume of:

V_(Na_2SO_4)=500 cm^(3)

Convert this to milliliters knowing that:

1 mL = 1 cm^3

Therefore:

V_(Na_2SO_4)=500 cm^3\cdot (1 mL)/(1 cm^3) =500 mL\cdot(1 L)/(1000 mL) =0.500 L

Also, we know that:

1 dm^3 = 1 L

Convert the molarity into mol/L:

1 (mol)/(dm^3)\cdot (1 dm^3)/(1 L)=1 (mol)/(L)

Multiply molarity by volume to find moles of sodium sulfate reacted:

n_(Na_2SO_4)=1 (mol)/(L)\cdot0.500 L=0.500 mol

According to stoichiometry of the equation, 1 mole of sodium sulfate produces 1 mole of sulfate, so 0.500 mol of sodium sulfate produce 0.500 mol of barium sulfate. That said, we have moles of barium sulfate produced. To find mass, let's multiply this amount of moles by the molar mass of barium sulfate:

m_(BaSO_4)=0.500 mol\cdot233.38 (g)/(mol) =116.69 g

Iron is produced in a blast furnace.Explain why most of the iron produced in a blast furnace is converted into steels.

Answers

It has nothing related to science . It is just dependent on the demand. If the demand for steel is high(as it is high)then most of it is used in making steel . Steel has many advantages thus it has a high demand.
I believe raw iron corrodes easily hence most of the iron is converted into steel , so as to increase its demand , life span and utility,
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