Please do these questions, will give brainliest

Dalton hypothesized that atoms are indivisible and that all atoms of an element are identical. It is now known that _____.

34kurt

Dalton hypothesized that atoms are indivisible and that all atoms of an element are identical. It is now known that atoms are divisible. The answer is letter C

8 0

3 years ago

Read 2 more answers

Question 3 (Molarity)

antiseptic1488 [7]

Answer:

The molarity of the solution is 1,03 M.

Explanation:

Molarity is a concentration measure that expresses the moles of solute (in this case HBR) in 1 liter of solution (1000ml). First we calculate the mass of 1 mol of HBr, to calculate the moles that are in 50 g of said compound:

Weight 1 mol HBr= Weight H + Weight Br= 1,01g + 79,90g= 80, 91 g/mol

80,91 g ----1 mol HBr

50,0 g------x= (50,0 g x1 mol HBr)/80,91 g= 0,62 mol HBr

600 ml solution-----0,62 mol HBr

1000ml solution------x= (1000ml solution x 0,62 mol HBr)/600 ml solution

x=1,03 moles HBr ---> The solution is 1,03M

8 0

3 years ago

A ball is equipped with a speedometer and launched straight upward. The speedometer reading four seconds after launch is shown a

Andrew [12]

Answer:

Question 1: 1 s after the motion starts

Question 2: 0 (just when the motion starts)

Explanation:

You will need to work with approximates values because the precision of the speedometers is low and you are requested to find approximate times.

1. From the speedometer shown at the right.

You can obtain how long the ball has been falling from the highest altitute it reached using the speed of 10 m/s shown by the speedometer at the right.

Free fall equation: Vf = Vo - gt

Vo = 0 ⇒ Vf = gt ⇒ t = Vf / g

For this problem, I recommend to work with a rough estimate of g: g = 10 m/s² ( I will tell you why soon)/

t = [10 m/s] / [10 m/s²] = 1 s

That is the time falling. Since four seconds after launch have elapsed, the upward time was 3 seconds. This will let you to calculate the launching speed.

2. Time when the speedometer displays a reading of 20 m/s

First, calculate the launching speed:

Vf = Vo - gt

Since the ball was 3 seconds going upward and the speed at the maximum altitude is 0 you get:

0 = Vo - gt

Vo = gt = 10 m/s² × 3 s = 30 m/s

Now, use the initial velocity to calculate when the ball is going upward with the speedometer reading is 20 m/s

20 m/s = 30 m/s - 10 m/s² × t

t = [ 30 m/s - 20 m/s] / [10 m/s²] = 1 s

Thus, the first answer is t = 1 s.

3. Time when the speedometer displays a reading of 30 m/s

This is the same speec estimated for the launching: 30 m/s.

So, this reading corresponds to the moment when the ball was launched.

Thus time is 0, i.e. it is the same instant of the launch.

If you had worked with g = 9.80 m/s², the time had been negative. This is due to the precision of the instruments.

That is why I recommended to work with g = 10 m/s².

6 0

3 years ago

Name two elements in the modern periodic table that break Mendeléey's rule that the elements should be arranged in order of rela

AnnZ [28]

I think it’s tellurium and iodine but I’m not 100% sure

4 0

3 years ago

Which of the following is NOT an exothermic reaction?

nignag [31]

Answer:

a) dissolving sugar in water to form a mixture of sugar and water

Explanation:

exothermic reaction is reaction in which is heat is released during the reaction and endothermic reaction is a reaction in which heat is needed or required for the reaction to take place

all the options excluding option A) is exothermic as during the process of formation of bonds in oxidation, heat is released. rusting too is a slow form of oxidation and thus an exothermic reaction.

dissolving sugar in water is not exothermic reaction because their is no heat released. the sugar molecules simply disperses in the water molecules and form a solution.

7 0

3 years ago