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Misha Larkins [42]
3 years ago
15

Which sample is a pure substance?

Chemistry
2 answers:
jeka57 [31]3 years ago
7 0

The correct answer is: A. a test tube of zinc oxide

Sunny_sXe [5.5K]3 years ago
6 0
A test tube of zinc oxide
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Explanation:

photosynthesis gives out oxygen so cellular respiration gives out carbon 4 oxide and take in oxygen

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Ill make u scream without the e :)<br><br><br><br> get out of my lawn
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Yep, this is my new pick up line

Explanation:

5 0
2 years ago
7. Which of the following represents the largest mass?
Tamiku [17]

Answer:

 10kg = 10 x 1000 = 10,000g

Explanation:

To know the quantity with the largest mass, we have to express all the units in grams:

for: 2 x 10mg = 2 x 10 x 10⁻³ = 0.02g

       0.001kg = 0.001 x 1000 = 1g

       1 x 10⁵ng = 1 x 10⁵ x 10⁻⁹ = 0.0001g

       2 x 10²cg = 2 x 10² x 10⁻² = 2g

       10kg = 10 x 1000 = 10,000g

Note:

              10⁻ ¹      deci(d)

              10⁻²       centi(c)

              10⁻³       milli(m)

            10⁻⁹         nano(n)

            10³           kilo(k)

   

5 0
4 years ago
Hydrogen peroxide decomposes spontaneously to yield water and oxygen gas according to the following reaction equation. 2H202(aq)
inn [45]

Answer : The temperature for non-catalyzed reaction needed will be 456 K

Explanation :

Activation energy : The energy required to initiate the reaction is known as activation energy.

According to the Arrhenius equation,

K=A\times e^{\frac{-Ea}{RT}}

Since, the rate for both the reaction are equal.

K_1=K_2

A\times e^{\frac{-Ea_1}{RT_1}}=A\times e^{\frac{-Ea_2}{RT_2}}

\frac{Ea_1}{T_1}=\frac{Ea_2}{T_2} ..........(1)

where,

Ea_1 = activation energy for non-catalyzed reaction = 75 kJ/mol

Ea_2 = activation energy for catalyzed reaction = 49 kJ/mol

T_1 =  temperature for non-catalyzed reaction = ?

T_2 = temperature for catalyzed reaction = 25^oC=273+25=298K

Now put all the given values in the above formula 1, we get:

\frac{Ea_1}{T_1}=\frac{Ea_2}{T_2}

\frac{75kJ/mol}{T_1}=\frac{49kJ/mol}{298K}

T_1=456K

Therefore, the temperature for non-catalyzed reaction needed will be 456 K

3 0
3 years ago
2KCIO3 ----------&gt; 2KCI + 302<br> How many moles of KCIO3 are needed to make 3.5 moles of KCL?
lyudmila [28]

Answer:

3.5 mol KClO3

Explanation:

Given 3.50 moles of KCl as the target amount in the problem, used the coefficient of the balanced chemical reaction involved to determine the number of moles of potassium perchlorate needed.

x mole of  KClO3  = 3.5 mol  KCl x [(2 mol KCl)/ (2 mol KClO3)] = 3.5 mol KClO3

x mole of  KClO3 = 3.5 mol KClO3

3 0
3 years ago
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