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AveGali [126]
3 years ago
5

Select all the correct answers.

Chemistry
2 answers:
swat323 years ago
8 0

Silver tarnishes and becomes black when exposed to oxygen:

              Diesel fuel burns when it is heated:

Mashutka [201]3 years ago
7 0

Answer:

              Silver tarnishes and becomes black when exposed to oxygen:

              Diesel fuel burns when it is heated:

Explanation:

                    Chemical Changes are those changes in which the chemistry at molecular level is changed as the starting material is converted in to a new and different final material. This change takes place with the breaking of old bonds and forming of new bonds respectively.

Silver tarnishes and becomes black when exposed to oxygen:

This is a chemical change as Silver a white and lustrous starting material is being converted into a tarnish black final material. However, Silver doesn't readily react with oxygen at normal conditions. It readily react with Sulfur containing compounds in air and produces black compound as Ag₂S.

Diesel fuel burns when it is heated:

Diesel is a mixture of hydrocarbons ranging approximately from C₁₀H₂₀ to C₁₅H₂₈. When these hydrocarbons are burnt they produces a new materials i.e. CO₂ and H₂O.

                             C₁₀H₂₀  +  15 O₂    →     10 CO₂  + 10 H₂O

Hence, it is also a chemical reaction.

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A balloon contains 11.1 g of nitrogen monoxide gas (NO). how many molecules are in the balloon?
grandymaker [24]

The number of molecules that are in balloon are = 2.227 x10^23 molecules

<h3> calculation</h3>

calculate the number of moles of NO

moles = mass/molar mass

molar mass  of NO = 14+ 16 = 30 g/mol

moles is therefore=  11.1 g/30g/mol= 0.37 moles

by use of Avogadro's constant that is

                                     1 mole= 6.02 x10^23  molecules

                                          0.37 =? molecules

=(6.02 x10^23 x  0.37 moles)/ 1mole=2.227 x10^23 molecules

4 0
3 years ago
How many moles of KNO3 are in 500 mL of 2.0 M KNO3?<br> ___ mol KNO3
weeeeeb [17]

Answer: 1mole

Explanation:

Mole = concentration× Volume (dm3)

Mole = 2× 500/1000

4 0
3 years ago
Read 2 more answers
Hydrogen bonds between adenine &amp; thymine or guanine and cytosine form ______ _______ that join the two strands of the DNA do
Kryger [21]

Base pairs.

Four + Five = Nine

The third letter in base is S.

IT ADDS UP.

7 0
3 years ago
A bottle containing air is initially at a temperature of 33 degrees C and a pressure of 0.81 atm. After being placed in the free
Georgia [21]

Answer:

The final pressure is 0.725 atm.

Explanation:

Gay Lussac's Law establishes the relationship between pressure and temperature of a gas when the volume is constant. This law says that when there is a constant volume, as the temperature increases, the pressure of the gas increases. And when the temperature is decreased, the pressure of the gas decreases. That is, pressure and temperature are directly proportional quantities.

Mathematically, Gay-Lussac's law states that, when a gas undergoes a constant volume transformation, the quotient of the pressure exerted by the gas temperature remains constant:

\frac{P}{T}  =k

When analyzing an initial state 1 and a final state 2, the following is satisfied:

\frac{P1}{T1}  =\frac{P2}{T2}

In this case:

  • P1= 0.81 atm
  • T1= 33 C= 306 K
  • P2= ?
  • T2= 1 C= 274 K

Replacing:

\frac{0.81 atm}{306 K}  =\frac{P2}{274 K}

Solving:

P2=274 K*\frac{0.81 atm}{306 K}

P2= 0.725 atm

<u><em>The final pressure is 0.725 atm.</em></u>

4 0
3 years ago
Neutralisation reactions worded formula
Liono4ka [1.6K]

Answer:

Hydrochloric acid + sodium → sodium chloride + water

NaOH +HCl → H2O and NaCl

Explanation:

salt is a neutral ionic compound. Let's see how a neutralization reaction produces both water and a salt, using as an example the reaction between solutions of hydrochloric acid and sodium hydroxide. The overall equation for this reaction is: NaOH +HCl → H2O and NaCl.

4 0
3 years ago
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