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3 years ago

14

True or false: Observing a physical property of a substance will change the substances' identity I NEEED HELLLPPPPP NOOOWWWW !!!

! PLEASEEEEE

1 answer:

andrew11 [14]3 years ago

8 0

Answer:

false

Explanation:

a physical property can be observed and stay the same but a chemical property can't

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BRAINLIEST PLEASE HELP!!!

Natalka [10]

Answer : first opinion and also last
Expiation : Note that these last two reactions, and 2H + 2H → 4He + γ, .Nuclear fusion is a reaction in which two nuclei are combined to form a larger nucleus. Nuclear fusion is a reaction in which two nuclei are combined, or fused, to form a larger nucleus. We know that all nuclei have less mass than the sum of the masses of the protons and neutrons that form them. The missing mass times c2 equals the binding energy of the nucleus—the greater the binding energy, the greater the missing mass.

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2 years ago

Ammonia is a main ingredient in fertilizers. The following reaction is used to synthesize ammonia, NH3. How many liters of ammon

PolarNik [594]

According to Balance chemical equation,

N₂ + 3 H₂ → 2 NH₃

1 mole of Nitrogen reacts with 3 moles of Hydrogen to produce 2 mole of Ammonia.
It is known that i mole of any gas at standard temperature and pressure occupies 22.4 L of Volume. So, we can also say,

22.4 L (1 × 22.4) of Nitrogen gas (in question it is taken in excess) reacts with 67.2 L (22.4 × 3) of Hydrogen gas to produce 44.8 L (22.4 × 2) of Ammonia.

Result:
44.8 L is the correct answer.

8 0

2 years ago

What is true about resonance structures? Select the correct answer below: They are all different molecules. The interconvert wit

3241004551 [841]

Answer:

The correct answer is: <em>They each partially describe the bonding in a molecule.</em>

Explanation:

Some chemical molecules cannot be described completely by using only one Lewis structure. In these cases, we can describe the molecule by drawing 2 or more Lewis structures, and the structures are called <u>resonance structures</u>. The overall molecular structure is explained by all the resonance structures together. So, they each describe the bonding in the molecule only partially.

7 0

2 years ago

What fraction of a Sr-90 sample remains unchanged after 87.3 years

jolli1 [7]

The answer is 1/8.

Half-life is the time required for the amount of a sample to half its value.
To calculate this, we will use the following formulas:
1. $(1/2)^{n} = x$ ,
where:
<span>n - a number of half-lives
</span>x - a remained fraction of a sample

2. $t_{1/2} = \frac{t}{n}$
where:
<span> $t_{1/2}$ - half-life
</span>t - <span>total time elapsed
</span><span>n - a number of half-lives
</span>
The half-life of Sr-90 is 28.8 years.
So, we know:
t = 87.3 years
<span> $t_{1/2}$ = 28.8 years

We need:
n = ?
x = ?
</span>
We could first use the second equation, to calculate n:
<span>If:
$t_{1/2} = \frac{t}{n}$ ,
</span>Then:
$n = \frac{t}{ t_{1/2} }$
⇒ $n = \frac{87.3 years}{28.8 years}$
⇒ $n=3.03$
<span>⇒ n ≈ 3
</span>
Now we can use the first equation to calculate the remained amount of the sample.
<span> $(1/2)^{n} = x$
</span>⇒ $x=(1/2)^3$
⇒ $x= \frac{1}{8}$ <span>
</span>

8 0

3 years ago

1)If I mixed salt in water I would expect the salt to:

zaharov [31]

Answer:

1)If I mixed salt in water I would expect the salt to: dissolve.

2) If I mixed starch in water I would expect the starch to: remain undissolved.

Explanation:

Hello,

In this case, since salt, which is commonly known as sodium chloride (NaCl) is an ionic compound, it is very likely to get dissolved in water, therefore, we would expect the salt to dissolve and form a liquid solution.

Moreover, since start is mainly composed by C-C, C-O and C-H bonds which are nonpolar, it we can say it is usually insoluble in water, therefore we will expect starch to remain undissolved but undergoing a process called gelatinization in which a suspension in formed until a slightly solid consistency.

Best regards.

4 0

2 years ago