I need help I don’t get it

A child is on a pogo stick. At the top of her jump, her kinetic energy (KE) = 0 J, her gravitational potential energy (GPE) = 10

krek1111 [17]

There would be 0 Potential energy, which eliminates A. There would be Spring energy, which eliminates C. So B and D are your 2 choices. Since the child is not moving just before the jump, there would be 0 Kinetic energy. So D.

7 0

3 years ago

Question 1(Multiple Choice Worth 4 points)

zubka84 [21]

<u>Answer </u>

Answer 1 : 28.9 g of CO is needed.

Answer 2 : Six moles of $H_{2}O$ over Nine moles of $O_{2}$

Answer 3 : Four over two fraction can be used for the mole ratio to determine the mass of Fe from a known mass of $Fe_{2}O_{3}$ .

Answer 4 : Mass of $O_{2}$ = (150 × 3 × 31.998) ÷ (232.29 × 1) grams

Answer 5 : 8.4 moles of sodium cyanide (NaCN) would be needed.

<u>Solution </u>

Solution 1 : Given,

Given mass of $Fe_{2}O_{3}$ = 55 g

Molar mass of $Fe_{2}O_{3}$ = 159.69 g/mole

Molar mass of CO = 28.01 g/mole

Moles of $Fe_{2}O_{3}$ = $\frac{\text{ Given mass of } Fe_{2}O_{3}}{\text{ Molar mass of } Fe_{2}O_{3}}$ = $\frac{55 g}{159.69 g/mole}$ = 0.344 moles

Balanced chemical reaction is,

$Fe_{2}O_{3}(s)+3CO(g)\rightarrow 2Fe(s)+3CO_{2}(g)$

From the given reaction, we conclude that

1 mole of $Fe_{2}O_{3}$ gives → 3 moles of CO

0.344 moles of $Fe_{2}O_{3}$ gives → 3 × 0.344 moles of CO

= 1.032 moles

Mass of CO = Number of moles of CO × Molar mass of CO

= 1.032 × 28.01

= 28.90 g

Solution 2 : The balanced chemical reaction is,

$2C_{3}H_{6}+9O_{2}\rightarrow 6CO_{2}+6H_{2}O$

From the given reaction, we conclude that the Six moles of $H_{2}O$ over Nine moles of $O_{2}$ is the correct option.

Solution 3 : The balanced chemical reaction is,

$4Fe+3O_{2}\rightarrow 2Fe_{2}O_{3}$

From the given balanced reaction, we conclude that Four over two fraction can be used for the mole ratio to determine the mass of Fe from a known mass of $Fe_{2}O_{3}$ .

Solution 4 : Given,

Given mass of $Zn(ClO_{3})_{2}$ = 150 g

Molar mass of $Zn(ClO_{3})_{2}$ = 232.29 g/mole

Molar mass of $O_{2}$ = 31.998 g/mole

Moles of $Zn(ClO_{3})_{2}$ = $\frac{\text{ Given mass of }Zn(ClO_{3})_{2} }{\text{ Molar mass of } Zn(ClO_{3})_{2}}$ = $(\frac{150\times 1}{232.29})moles$

The balanced chemical equation is,

$Zn(ClO_{3})_{2}}\rightarrow ZnCl_{2}+3O_{2}$

From the given balanced equation, we conclude that

1 mole of $Zn(ClO_{3})_{2}$ gives → 3 moles of $O_{2}$

$(\frac{150\times 1}{232.29})moles$ of $Zn(ClO_{3})_{2}$ gives → $[(\frac{150\times 1}{232.29})\times 3] moles$ of $O_{2}$

Mass of $O_{2}$ = Number of moles of $O_{2}$ × Molar mass of $O_{2}$ = $[(\frac{150\times 1}{232.29})\times 3] \times 31.998 grams$

Therefore, the mass of $O_{2}$ = (150 × 3 × 31.998) ÷ (232.29 × 1) grams

Solution 5 : Given,

Number of moles of $Na_{2}SO_{4}$ = 4.2 moles

Balanced chemical equation is,

$H_{2}SO_{4}+2NaCN\rightarrow 2HCN+Na_{2}SO_{4}$

From the given chemical reaction, we conclude that

1 mole of $Na_{2}SO_{4}$ obtained from 2 moles of NaCN

4.2 moles of $Na_{2}SO_{4}$ obtained → 2 × 4.2 moles of NaCN

Therefore,

The moles of NaCN needed = 2 × 4.2 = 8.4 moles

3 0

3 years ago

Read 2 more answers

I WILL GIVE THE BRAINLIEST

lubasha [3.4K]

Ans 1. Both

Ans 2. Once inside plants, carbon moves through food chains, where organisms become nutrients including herbivores, carnivores and ultimately, decomposers. Once buried in the soil, carbon can be converted into fossil fuels over long periods of time and then also reenter the atmosphere by combustion. The Law of Conservation of Matter states that matter cannot be created or destroyed. The carbon cycle is an example of the Law

Ans 3. Most of the chemical energy needed for life is stored in organic compounds as bonds between carbon atoms and other atoms. The law of conservation of energy states that energy can not be created or destroyed. Thus, just like matter energy is also conserved in the process.

Hope it helps

3 0

3 years ago

If a fish gets squirted with ink it will swim slower

Natali5045456 [20]

Answer:cool

Explanation:

5 0

3 years ago

When the fish-tank water has a pH of 8.0, the hydronium ion concentration is 1.0 × 10-8 mole per liter. What is the hydronium io

Oduvanchick [21]

You must know and use the formula for pH.

pH = - log [H3O+], where [H3O+] is the molar concentration of hydronium ion.

So, when pH is 8.0 => 8.0 = - log [H3O+] and you can use antilogarithm (the inverse function of logarithm) to find [H3O+], in this way:

[H3O+] = 10^-8 = 1 * 10 ^-8 M

When, pH = 7.0 =>

7.0 = - log [H3O+] => [H3O+] = 1 * 10^ -7 M

Answer: 1*10^-7 mole / liter

5 0

3 years ago