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3 years ago

Sharping a pencil leaves behind pencil shavings. Is sharpening pencil a physical or chemical change

Chemistry

1 answer:

Deffense [45]3 years ago

6 0

Physical, since you are physically changing its appearance

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How many moles are in 5.0 x 1025 atoms of iron

Mnenie [13.5K]

1 mole --------------- 6.02 x 10²³ atoms
( moles iron) -------- 5.0 x 10²⁵ atoms

( moles iron ) = 5.0 x 10²⁵ x 1 / 6.02 x 10²³

moles iron = 5.0 x 10²⁵ / 6.02 x 10²³

= 83.05 moles of iron

hope this helps!

8 0

3 years ago

How can you find out what substances

nlexa [21]

Answer: Melting or boiling

Explanation:

Melting or boiling point is another property that scientists can use to identify a substance. Melting point is the temperature at which a substance changes from solid → liquid. Boiling point is the temperature at which a substance changes from liquid → gas.

6 0

2 years ago

Different isotopes of a particular element contain the same number of

zimovet [89]

Electrons and protons, but not neutrons.

8 0

3 years ago

. The net ionic equation for the reaction that occurs during the titration of nitrous acid with sodium hydroxide is (a) HNO2 Na

hjlf

Answer:

$H^+_{(aq)}+OH^{-}_{(aq)}\rightarrow H_2O_{(l)}$

Explanation:

Complete ionic equation : In complete ionic equation, all the substance that are strong electrolyte and present in an aqueous are represented in the form of ions.

Net ionic equation : In the net ionic equations, we are not include the spectator ions in the equations.

Only the species which are present in aqueous state dissociate.

Spectator ions : The ions present on reactant and product side which do not participate in a reactions. The same ions present on both the sides.

(a)

The balanced molecular equation will be,

$HNO_2_{(aq)}+NaOH_{(aq)}\rightarrow H_2O_{(l)}+NaNO_2_{(aq)}$

The complete ionic equation in separated aqueous solution will be,

$H^+_{(aq)}+NO_2^-_{(aq)}+Na^+_{(aq)}+OH^{-}_{(aq)}\rightarrow H_2O_{(l)}+Na^+_{(aq)}+NO_2^-_{(aq)}$

In this equation the species present are, $Na^+\text{ and }NO_2^-$ are the spectator ions.

Hence, the net ionic equation contains specie is

$H^+_{(aq)}+OH^{-}_{(aq)}\rightarrow H_2O_{(l)}$

6 0

2 years ago

A single serving bag of snack chips contains 65.0 Cal. Assuming that all of the energy from eating these chips goes toward keepi

AveGali [126]

Answer:

= 62.1 hours

Explanation:

Energy provide by the serving is 65 cal

= 65 cal × 4.184 Kj = 271.96 kJ

271.96 KJ = 271960 J

Energy required for 1minute of energy

= 73 x 1

= 73 J/min

So, 271960 joules will be required for 271960 heart beat

Minutes = 271960 / 73

= 3593.94 minutes

Time in hours = 3725.429 / 60

= 62.1 hours

5 0

3 years ago