7. (a) Using two examples, explain how covalent compounds are formed. [4 marks]
(b) State three physical properties of covalent compounds. [3 marks]
(c) Describe an experiment how you can carry out an experiment to investigate one of the properties mentioned above. [3 marks]

8. (a) Using two examples, explain how covalent compounds are formed. [14 marks]
(b) State three physical properties of covalent compounds.[3 marks]
Describe an experiment how you can carry out an experiment to investigate one of the properties mentioned above. [3 marks]​

Answer:

[tex]\boxed {\boxed {\sf A. \ 186.94 \ L}}[/tex]

Explanation:

We are asked to find the original volume of a gas given a change in temperature. Since pressure remains constant, we are only concerned with volume and temperature, so we use Charles's Law. This states the volume of a gas is directly proportional to the temperature. The formula for this law is:

[tex]\frac {V_1}{T_1}= \frac{V_2}{T_2}[/tex]

The gas begins with a temperature of 450 Kelvin, but the volume is unknown.

[tex]\frac {V_1}{450 \ K }= \frac{V_2}{T_2}[/tex]

The gas is cooled to 248.9 Kelvin and the gas occupies a volume of 103.4 liters.

[tex]\frac {V_1}{450 \ K }= \frac{103.4 \ L}{248.9 \ K}[/tex]

Since we are solving for the original volume, we must isolate the variable V₁. It is being divided by 450 Kelvin. The inverse operation of division is multiplication, so we multiply both sides of the equation by 450 K.

[tex]450 \ K \frac {V_1}{450 \ K }= \frac{103.4 \ L}{248.9 \ K}* 450 \ K[/tex]

[tex]V_1= \frac{103.4 \ L}{248.9 \ K}* 450 \ K[/tex]

The units of Kelvin cancel.

[tex]V_1= \frac{103.4 \ L}{248.9 }* 450[/tex]

[tex]V_1= 0.4154278827 \ L *450[/tex]

[tex]V_1= 186.9425472 \ L[/tex]

Round to the nearest hundredth. The 2 in the thousandths place tells us to leave the 4 in the hundredth place.

[tex]V_1 \approx 186.94 \ L[/tex]

The original volume is approximately 186.94 liters and Choice A is correct.

Answer:

D

Explanation:

P = Pressure

V = Volume

n = Moles

R = .08206 (because we're using liters)

T = Temperature (as K)

P(50) = (4)(.08206)(308)

P(50) = 101.09792

Divide both sides by 50

P(50)/50 = 101.09792/50

P = 2.0219584

Answer:

[tex]\boxed {\boxed {\sf D. \ 2.02 \ atm}}[/tex]

Explanation:

We are asked to find the pressure of helium gas using the ideal gas law.

[tex]PV= nRT[/tex]

In this formula P is the pressure, V is the volume, n is the number of moles of gas, R is the universal gas constant, and T is the temperature.

The pressure is unknown and we are solving for it. The volume is 50 liters, there are 4 moles of helium gas, the universal gas constant is 0.08206 L *atm/ mol * K, and the temperature is 308 Kelvin.

[tex]\bullet \ V= 50 \ L \\\bullet \ n= 4 \ mol \\\bullet \ R = \frac {0.08206 \ L * atm}{mol *K}\\\bullet \ T= 308 \ K[/tex]

Substitute these values into the formula.

[tex]P * 50 \ L= 4 \ mol * \frac {0.08206 \ L * atm}{mol *K} * 308 \ K[/tex]

Multiply on the right side. The units of moles (mol)  and Kelvin (K) cancel each other out.

[tex]P* 50 \ L = 4 * 0.08206 \ L *atm * 308[/tex]

[tex]P*50 \ L =0.32824 \ L * atm *308[/tex]

[tex]P* 50 \ L = 101.09792 \ L * atm[/tex]

We are solving for the pressure, so we must isolate the variable P. It is being multiplied by 50 liters. The inverse operation of multiplication is division, so divide both sides by 50 L.

[tex]\frac {P* 50 \ L}{50 \ L} = \frac {101.09792 \ L * atm}{50 \ L}[/tex]

[tex]P= \frac {101.09792 \ L * atm}{50 \ L}[/tex]

The units of liters (L) cancel.

[tex]P= \frac{101.09792}{50 } \ atm[/tex]

[tex]P= 2.0219584 \ atm[/tex]

If we round to the nearest hundredth place the 1 in the thousandth place tells us to leave the 2 in the hundredth place.

[tex]P \approx 2.02 \ atm[/tex]

The pressure is approximately 2.02 atmospheres and choice D is correct.

Answer:

2H2O2 + NaClO → NaClO3 + 2H2O

Answer:

C

Explanation:

Answer:

45 °C.

Explanation:

From the question given above, the following data were obtained:

Heat (Q) = 1125 J

Mass (M) = 250 g

Final temperature (T₂) = 55 °C

Specific heat capacity (C) = 0.45 J/gºC

Initial temperature (T₁) =?

The initial temperature of the iron can be obtained as illustrated below:

Q = MC(T₂ – T₁)

1125 = 250 × 0.45 (55 – T₁)

1125 = 112.5 (55 – T₁)

Divide both side by 112.5

1125/112.5 = 55 – T₁

10 = 55 – T₁

Collect like terms

10 – 55 = –T₁

–45 = –T₁

Multiply through by –1

45 = T₁

T₁ = 45 °C

Therefore, the initial temperature of the iron is 45 °C

Answer:

A Calorimeter is a device used to measure the amount of heat involved in a chemical or physical process.

Explanation:

Ex- when an exothermic reaction ( accompanied by or requiring absorption of heat)occurs in solution in a calorimeter, the heat produced by the reaction is absorbed by the solution increasing its temperature.

   - When an endothermic reaction (Heat evolving reaction) occurs, the heat required is absorbed from the thermal energy of the solution, decreasing its temperature.

A burning piece of coal which is releasing heat due to its combustion and is transferred to water.

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Alkynes are called the hydrocarbons. Ethyne is an important alkyne which is used in oxyacetylene gas cutting. A hydrocarbon containing a carbon-carbon triple bond is the alkyne. The correct option is C.

In organic chemistry, an alkyne is defined as the unsaturated hydrocarbon containing at least one carbon-carbon triple bond. The alkynes are unsaturated hydrocarbons and their general formula is CₙH₂ₙ₋₂ and the triple bond is known as the acetylene bond.

Many alkynes are found in nature. Ethyne is the first member of the alkyne family in which two carbon atoms are connected by a triple bond. Almost all alkynes are also found to be hydrophobic in nature.

Alkynes show three types of isomerism like chain isomerism, position isomerism and functional isomerism. The triple bond present in the alkynes is its functional group.

Thus the correct option is C.

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Answer:

O. compounds

Explanation:

[tex]{ \underline{ \sf{ \blue{christ \: † \: alone}}}}[/tex]

Answer:

volume = mass/ densidad

0.88g/cm3 = 880kg/m3

v=20kg/880kg/m3

v=0.02272727272

o puede ser 0.0227

o tambien puede ser 0.023

Answer:

a

Explanation:

Answer:

The answer is "1.8 g diamond includes 9.03e22 atoms".

Explanation:

Given:

Weight of 9-carat diamond = 1.8 g

 [tex]\therefore\\\\[/tex]

weight of 1-mole carbon  =12 g

[tex]\because[/tex]

calculating the moles which are available into  18 g carbon weight:

 x= Carbon moles weight in 1.8 g

[tex]1 - mol\ C = 12 g\\\\x - mol\ C = 1.8 g\\\\\to x = \frac{(1.8 \ g \times 1\ mol\ C)}{ 12 \ g}\\\\\to x = 0.15\ moles[/tex]

In 1 mole element associated with Avogadro's number that is [tex]6.02 \times 10^{23}\\\\[/tex]

 Carbon includes in 1 mol[tex]=6.02 \times 10^{23}\ atoms\\\\[/tex]

0.15 mol of carbon includes:

[tex]= 0.15 \times 6.02 \times 10^{23} = 9.03 \times 10^{22}\ atoms.[/tex]

Using the scientific notation:

0.15 mol of carbon includes:  9.03e22 atoms. So,   1.8 g diamond includes 9.03e22 atoms.

Answer:

D - g/mol

step by step method

Answer:

13.B 0.15 M KBr

14.C 1 M C²h⁵OH

15.D 0.1 M C⁶H¹²o⁶

16.A 2 K² SO⁴

17.A 2 M K² SO⁴

18.D 0.028 M KBr

19.A 1 M Nal

20.B 0.1 M AICI³

Answer:

2KMnO₄ (aq) + 10KBr (aq) + 8H₂SO₄ (aq) -> 2MnSO₄ (aq) + 5Br₂ (aq) + 6K₂SO₄ (aq) + 8H₂O (l)

oxidizing agent = KMnO₄

reducing agent = KBr

Explanation:

KMnO₄ -> 2Mn⁷⁺ + 10e⁻ = 2Mn²⁺

KBr -> 10Br⁻⁺ - 10e⁻ = 10Br⁰

is any musical instrument that creates sound primarily by the vibration of the instrument itself without the use of air flow

Answer:

a quantity chosen as a standard in terms of which other quantities may be expressed.

Explanation:

Explanation:

Unit is a standard physical quantity defined and adopted by convention,with other quantity of same kind.

Answer:

I think its sugar breaking down into watee and carbon when it is heated

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Answer: Qualitative data typically consists of words while quantitative data consists of numbers.

Explanation:

Answer:

I put the right structures in the pictures for you

D. Water is used up, Oxygen is produced and Chlorophyll is necessary, but remains unchanged.

Answer:(b)liquid water is correct option . Because it is a molecular solid and molecular solid has weak interparticle forces of attraction

Explanation:

Answer:

94.8454

Explanation:

Let volume be V

Let Temperature be T

V1= 92

T1= 3C but to kelvin 273+3= 300K

V2= ?

T2= 18 C but to kelvin 18+273= 291

[tex] \frac{v1}{t1} = \frac{v2}{t2} [/tex]

[tex] \frac{92}{300} = \frac{v2}{291} [/tex]

[tex]v2 \times 300 = 92 \times 291[/tex]

[tex]v2 = \frac{92 \times 291}{300} [/tex]

[tex]v2 = 94.8454[/tex]

Answer:

The mineral forms gas bubbles when a sample is stored in water

Answer:

option a and c both are correct

Explanation:

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The pairs of compounds have the same empirical formula are:

a. acetylene, C₂H₂, and benzene, C₆H₆ and

c .nitrogen dioxide, NO₂, and di nitrogen tetroxide, N₂O₄

The empirical formula of a compound is defined as the formula that shows the ratio of elements present in the compound, but not the actual numbers of atoms found in the molecule.

In some cases, the empirical formula is the same as the molecular formula, which gives the actual number of atoms in a compound (e.g., H₂O).Otherwise, the molecular formula is a multiple of the empirical formula (e.g., CH₂O is the empirical formula for glucose, C₆H₁₂O₆).

Examples of empirical formulas:

Glucose has a molecular formula of C₆H₁₂O₆. It contains 2 moles of hydrogen for every mole of carbon and oxygen. The empirical formula for glucose is CH₂O.

The molecular formula of ribose is C₅H₁₀O₅, which can be reduced to the empirical formula CH₂O.

The pair with empirical formula is  acetylene, C₂H₂, and benzene, C₆H₆ and

nitrogen dioxide, NO₂, and di nitrogen tetroxide, N₂O₄

Thus, option (A) and (C) are correct.

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Answer:

Physical properties are defined as the properties which can be observed without changing their chemical composition.

For example, color, volume, and molecular weight.

Chemical properties can be defined as, a properties that can be seen only after changing the substance's chemical identity.

For example, reactivity, toxicity, and flammability.

The fundamental differences between physical and chemical properties are as follows:

Chemical properties are related to chemical bonds of the substance, while physical properties are not.

In chemical properties, the chemical identity of substance changes while physical properties does not have any change.

Chemical properties predict the reaction of a substance, while physical properties only describe the appearance of the substance.

Explanation:

Answer:

Why is the unit of force called a derived unit? That's because the Newton is defined in terms of other units which are more fundamental. One Newton is the force required to accelerate a mass of one kilogramme at the rate of one metre per second squared.

Answer:

99

Explanation:

it is matter so it and it has.bein 99

Answer:

0.289J of heat are added

Explanation:

We can relate the change in heat of a substance with its increasing in temperature using the equation:

q = m*ΔT*S

Where Q is change in heat

m is mass of substance (In this case, 0.0948g of water)

ΔT = 0.728°C

S is specific heat (For water, 4.184J/g°C)

Replacing:

q = 0.0948g*0.728°C*4.184J/g°C

q = 0.289J of heat are added

Answer:

5.ethanol and carbon dioxide

6.it contains ethyl alcohol which can be effective at killing viruses and bacteria