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3 years ago

15

A soccer player kicks a soccer ball. The ball travels 20 meters before landing on the ground. The ball stayed in the air for 5 s

econds. What is the average speed of the ball? *

1 answer:

natulia [17]3 years ago

5 0

Answer:

4 meters per second

Explanation:

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A 453 g piece of glass at 25.7∘C is left outside on a sunny day. How much heat must the glass absorb from the sun in order to re

Tju [1.3M]

Answer:

Q = 5555.6J

Explanation:

Mass of glass piece, m = 453g

initial temperature = 25.7°C

temperature to be attained = 40.3°C

⇒change in temperature, Δt = 40.3 - 25.7 = 14.6°C

specific heat of glass, s = 0.840J/g°C

Heat absorbed, Q = msΔt

⇒Q = 453×0.840×14.6 = 5555.592J

⇒<u>Q = 5555.6J</u> (rounded to the nearest tenth)

7 0

3 years ago

Solid sodium hydroxide <br> NaOH<br> decomposes into gaseous water and solid sodium oxide .

kari74 [83]

What about it do you want answered

8 0

3 years ago

What is the symbol of the ion with 36 electrons and a +2 charge?

AlladinOne [14]

Answer:

Strontium

Explanation:

The atomic number of strontium is 38.

It has 38 electrons.

It is alkaline earth metal. It has two valance electrons.

Strontium loses its two electrons and form cation with +2 charge.

Electronic configuration;

Sr₃₈ = [Kr] 5s²

The valance electrons present in 5s are lost by strontium atom and form Sr⁺² cation.

it is yellowish-white metal.

It is highly reactive.

It form salt with halogens.e.g

Sr + Br₂ → SrBr₂

IT react with oxygen and form oxide.

2Sr + O₂ → 2SrO

this oxide form hydroxide when react with water,

SrO + H₂O → Sr(OH)₂

With nitrogen it produced nitride,

3Sr + N₂ → Sr₃N₂

With acid like HCl,

Sr + 2HCl → SrCl₂ + H₂

3 0

3 years ago

1. A gas having the following composition is burnt under a boiler with 50% excess air.

jeka94

The composition of the stack gas are :

$CH_4$ = 0.8713

$C_3H_8$ = 0.0202

CO = 0.107

<h3 /><h3>What is a mole fraction?</h3>

The ratio of the number of moles of one component of a solution or other mixture to the total number of moles representing all of the components.

Assuming 100 g of the stack gas. Calculate the mass of each species in this sample according to their percentages.

Mass of $CH_4$ : 70% of 100 g = 70 g

Mass of $C_3H_8$ : 15% of 100 g = 15 g

Mass of CO : 15% of 100 g = 15 g

Now calculate the number of moles of each species:

Number of moles of $CH_4$ : $\frac{70 g}{16.04 g/mol}$ = 4.3 mole

Number of moles of $C_3H_8$ : $\frac{15 g}{144.1 g/mol}$ = 0.10 mole

Mass of CO : $\frac{15 g}{28.01 g/mol}$ = 0.53 mole

Now to calculate the mole fraction of each we use the formula:

Mole fraction of $CH_4$ : $\frac{4.3}{4.935}$ = 0.8713

Mole fraction of $C_3H_8$ : $\frac{0.10}{4.935}$ = 0.0202

Mole fraction of CO : $\frac{0.53}{4.935}$ = 0.107

Hence, composition of the stack gas are:

$CH_4$ = 0.8713

$C_3H_8$ = 0.0202

CO = 0.107

Learn more about mole fraction here:

brainly.com/question/13135950

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8 0

2 years ago

Assuming equal concentrations, arrange these solutions by pH.

LenKa [72]

Answer:

Highest pH(most basic)

Sr(OH)2(aq)

KOH (aq)

NH3(aq)

HF (aq)

HClO4(aq)

Lowest pH(most acidic)

Explanation:

The concentration of H+ ion will determine the pH of a solution. The pH actually reflects the ratio of H+ ion and OH- since both of them can combine into water. Solution with more H+ ion will have a lower pH and called acidic, while more OH- will have high pH and be called basic. Strong acid/base will be ionized more than weak acid/base.

Sr(OH)2(aq) = strong base, release 2 OH- ion per mole

KOH (aq) = Strong base, release 1 OH- per mole

NH3(aq) = weak base, release less than 1 OH- per mole

HF (aq) =strong acid, release 1 H+ per mole

HClO4(aq) = stronger acid, release 1 H+ per mole

8 0

3 years ago