CHEMISTRY MIDDLE SCHOOL

How Long can we POSSIBLY Hold our Breaths underwater?

Answers

Answer 1
Answer: It really depends on the person, people with bigger lungs can hold their breath longer than those with smaller lungs
Answer 2
Answer: i dont understand what you are trying to ask but the world record is 20 minutes but , most people can only hold their breath for two minutes.

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Select the correct answer.If a silver nitrate solution is added to excess sodium sulfide, this reaction takes place: 2AgNO3(aq) + Na2S(aq) → Ag2S(s) + 2NaNO3(aq). Suppose you use 0.0150 liter of a 2.50 M solution of silver nitrate. Assuming the reaction goes to completion, how much silver sulfide is produced? Use the periodic table. A. 1.49 g B. 4.65 g C. 9.30 gD. 18.6 g
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Which of these period three elements from the periodic table would you predict to be the MOST metallic? A)Al
B)Ar
C)Cl
D)Si

Answers

Al, since it is the only metal in that list

A is obiviously the answer here.

What are the two fundamental portions of an atom?​

Answers

Number of Protons in an Uncharged Atom
The two main components of an atom are the nucleus and the cloud of electrons. The nucleus contains positively charged and neutral subatomic particles, whereas the cloud of electrons contains tiny negatively charged particles.

If molarity = moles liter , then how many grams of NaCl are needed to make 1 liter of a 0.1 M solution? A) 0.0584 g NaCl B) 3.246 g NaCl C) 5.844 g NaCl D) 58.44 g NaCl

Answers

 The grams  of NaCl   that needed  to make 1L  of a 0.1 M solution  is  

5.845 g (answer C)

 calculation

Step 1: find the  moles of NaCl

moles  = molarity  x  volume  in liters

molarity = 0.1 M =0.1 mol/l

= 1 L x 0.1 Mol/L = 0.1 moles


Step 2: find  the   mass  NaCl

mass =  moles x  molar mass

From  periodic  table   the molar mass of NaCl  = 23 +35.45 =58.45 g/mol

mass= 0.1 moles  x 58.45 g/mol =5.845 g appropriate ( answer C)


Answer : Option C) 5.844 g NaCl

Explanation :

To calculate the number of grams of NaCl that would be needed to make 0.1 M of solution we have to calculate;

  1. The molecular weight of sodium chloride (NaCl) which is 58.44 g, so one gram molecular weight will be= 1 mole which is 58.44 g.
  2. By dissolving 58.44 g of NaCl upto the final volume of 1 litre, one can get 1 M NaCl solution.
  3. So, to make 0.1 M NaCl solution we have to dilute the mass of salt to 1000 ml of solution as follows;
  4. 0.1 M NaCl solution will require 0.1 x 58.44 g of NaCl = 5.844 g. of NaCl.

Which element has atoms with the strongest attraction for electrons in a chemical bond?(1) chlorine (3) fluorine

(2) nitrogen (4) oxygen

Answers

fluorine by far has the greatest
answer: (3) fluorine...........

Sonya is studying a nonmetal element. She learns that the element is like other elements in its group because it can bond to form a salt or an acid. She also learns that the element is the most reactive element in its group. Which element is Sonya most likely studying?

Answers

Answer is: fluorine (F).

Group 17 (halogens) elements: fluorine (F), chlorine (Cl), bromine (Br) and iodine (I). They are very reactive and easily form many compounds.  

Halogens need to gain one electron to have electron cofiguration like next to it noble gas.  

Fluorine has atomic number 9, it means it has 9 protons and 9 electrons.

Fluorine tends to have eight electrons in outer shell like neon (noble gas) and gains one electron in chemical reaction.  Fluorine is most reactive nonmetal.

Electron configuration of fluorine: ₉F 1s² 2s² 2p⁵.  

Electron configuration of neon: ₁₀Ne 1s² 2s² 2p⁶.  
She is studying Fluorine. it is the most active element on the periodic table.

_______ rock can be changed directly into _______ rock with the application of heat and pressure.

Answers

 a rock can be changed directly into metamorphic rock with the application of heat and pressure.

Sedimentary, Metamorphic
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