CHEMISTRY MIDDLE SCHOOL

Which of the statements about elements is true? 1. No two elements have the same kind of atom.
2. Scientists have identified a little less than 100 elements.
3. The atoms of all elements have the same mass and volume.
4. The atoms of all elements have different masses but the same volume.

Answers

Answer 1
Answer:

No two elements have the same kind of atom is the statement true about elements therefore, option (1) is correct.

What do you mean by the elements ?

An element is a substance whose atoms all have the same number of protons  , in other words we can say that   all atoms of a given element have the same number of atoms.

Characteristics of an element -:

The main characteristic of an element is that it is a pure substance. This means that it cannot be broken down any further and into any other substance.

Elements describes about the elements  interact with the environment around them, especially temperatures and when they are placed into different substances .

No two elements have the same kind of atom is the statement true about elements hence , option (1) is correct.

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Answer 2
Answer:

Answer:

No two elements have the same kind of atom.

Explanation:


Related Questions

COLLEGE

In 100 grams of sweet peas there are 14.5 carbohydrates,5.7 grams of sugars,5.1 grams of dietary fiber, 5.4 grams of protein and 0.4 grams of fat what is the percent composition of each?

Answers

14.5 % carb
5.7% sugar
5.1% fiber
5.4% protein
0.4% fat
MIDDLE SCHOOL

Why is it necessary to find the percent yield of a reaction? A. to determine the efficiency of the reaction B. to determine the amount of reactants in the reaction C. to determine the amount of products in the reaction D. to determine the limiting reactant of the reaction

Answers

Answer:

A. to determine the efficiency of the reaction

Explanation:

  • Percentage is the ratio of the actual yield to theoretical yield as a percentage. It is calculated by dividing the actual yield by theoretical yield then multiplying by 100%.
  • Calculation of percentage yield is important as it helps in the determination of efficiency of a reaction. For example in most industries for the purpose of making the most product with the least waste.
  • Additionally, calculating the percentage yield helps in determining other products that may be formed during the reactions.
HIGH SCHOOL

Rank from most conductive to least conductive: AlCl3, C6H12O6, KBr, C3H7OOH ??

Answers

Answer:

The order is:

AlCl₃ > KBr > C₃H₇COOH > C₆H₁₂O₆

Explanation:

A compound is conducting in nature (in soluble form) if it is ionic.

More the ions produced by a compound more the conductive the compound is.

In the given compounds C₆H₁₂O₆ is non electrolytic or non ionic. It will dissolve in water and will not furnish any ion thus it will be non conducting (least)

C₃H₇COOH: It is a weak electrolyte and will dissociate very less in water and thus it will be conducting but less than a strong elecrolyte.

KBr and AlCl₃ both are ionic and will dissociate completely however AlCl₃ will produce four ions while KBr will give only two ions per molecule.

Hence AlCl₃ is more conducting

The order is:

AlCl₃ > KBr > C₃H₇COOH > C₆H₁₂O₆

One needs to rank from the most conductive to the least conductive among the formulas that are given in the question. The ranking will be as given below.
1. AlCl3
2. KBr
3. C3H7OOH
4. C6H12O6

I hope that this is the answer that you were looking for and the answer has actually come to your desired help.
HIGH SCHOOL

A student sets up two reactions. reaction 1 uses 0.230 mol/l of reactant, and reaction 2 uses 0.570 mol/l of reactant. how many times faster is reaction 2 compared to reaction 1?

Answers

Answer: The rate of second reaction is times the rate of the first reaction.

Explanation:

For the first reaction where concentration o the reactant is [A]= 0.230 mol/L

..(1)

For the second reaction where concentration o the reactant is [A]= 0.570 mol/L

{tex]R_2=k\times [A]^a=k\times [0.570 mol/L]^a[/tex]...(2)

Dividing (2) and (1)

The rate of second reaction is times the rate of the first reaction.

Assuming that the rate of reaction is of first order, so that the rate is only dependent on the concentration A:

rate = - k A

 

So to know how much faster is reaction 2 compared to reaction 1, simply take the ratio of concentrations:

0.570 / 0.230 = 2.48


So reaction 2 is about 2.48 times faster.

HIGH SCHOOL

A solution of ammonia has a pH of 11.8. What is the concentration of OH– ions in the solution? Useful formulas..

Answers

The concentration of hydroxide ions in the given aqueous solution is equal to  6.3 ×10⁻³ M.

What is the pOH?

pOH can be calculated from the negative logarithm of the concentration of hydroxide ions in the given aqueous solution.

Mathematically, the formula of the pOH can be represented as shown below:

pOH = - log ([OH⁻ ])                                                

and pH  +  pOH  =  14                                                       ..............(1)

Where [OH⁻] is representing the concentration of hydroxide ions in an aqueous solution.

Given, the value of the pH of the ammonia solution, pH = 11.8

Substitute the value of the pH in equation (1):

pH + pOH  =  14    

11.8  - log [OH⁻] = 14

- log [OH⁻] = 14 -11.8

log [OH⁻] = - 2.2

[OH⁻] = 6.3 × 10⁻³ M

Therefore, the concentration of the hydroxide ions is equal to 6.3 ×10⁻³ M.

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They are asking you for OH- ions concentration, which is why you have to find the pOH of the solution. You can easily do this with this formula:

pH + pOH = 14

Solve for pOH and you get:

pOH = 14 - pH

Replace the pH with it's value:

pOH = 14 - 11.8
pOH = 2.2

Now that you have the pOH you can find the concentration of OH- ions with this formula:

pOH = -log[OH-]

Solve the formula for [OH-] and you get:

[OH-] = 10^(-pOH)

Now replace pOH with it's value:

[OH-] = 10^(-2.2)
[OH-] = 0.006309 M

The concentration of OH- atoms is 0.006309M or in the scientific notation 6.309×10^(-3)M
HIGH SCHOOL

Over-encouraging lesser skilled players can lead to embarrassment.
a. True
b. False

Answers

Answer: Option (a) is correct.

Explanation:

A person with less skills needs to work more or practice more on his abilities in order to improve their athletic ability to build a stronger team.

Over encouragement to lesser skilled person can lead to the development of over confidence. As after over encouragement, the less skilled person can have the illusion of knowing each and everything which is not true for anyone.

As no one is perfect, therefore, over-encouraging lesser skilled players can lead to embarrassment.

My answer would be a. True
HIGH SCHOOL

A forklift raises a crate weighing 8.35 × 10Æ newtons to a height of 6.0 meters. What amount of work does the forklift do?

Answers

13.4998JOULES it does not put anymore work lol.

Answer:

13.4998 joules. plato 13.4

Explanation:

HIGH SCHOOL

What chemical reaction happens when mixing iron and copper

Answers

i looked it up watched a video and i saw that rusting occured hope this helped let me know if it did and rate me from ok good great or godly.

:)

COLLEGE

What is the mass, in grams, of 28.80 ml of acetone?

Answers

The given question is incomplete. The complete question is as follows.

What is the mass, in grams, of 28.80 ml of acetone? Acetone (nail polish remover) has a density of 0.7857 .

Explanation:

It is known that density is the mass of a substance occupied in per unit volume of the object.

Mathematically,    Density =

Therefore, putting the given values into the above formula as follows.

               Density =

   0.7857 =   (1 ml = 1 )

                 mass = 22.62 g

Thus, we can conclude that mass of given acetone is 22.62 g.

density of acetone in gm/cm^3 is 0.791

=28.80cm^3*0.791 g/cm63

=22.78 g

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