2.
Corona virus has a spherical shape. Its diameter is approximately 120 nm. How
many of them can sit side by side to form a circle around a piece of human hair.
Take the diameter of a hair as 50 um. (Select the nearest value to your calculation
result)
a) 1.23x10 12
b) 4.45 x106
C) 1312
d) 417

Answer:

Chemistry can be applicable in many aspects which are

i) At school, through getting knowledge you can assess different aspect of chemistry, eg production of Chemicals.

ii) At hospital, also chemistry can be applicable in hospital because most of medicine and other materials are made up from chemistry application.

iii) Agriculture, through agricultural materials it simply because you can get more efficient through planted by using manures and fertilizer which are made up from chemistry application.

Answer:  [tex]Zn+2HCl\rightarrow ZnCl_2+H_2[/tex]

Explanation:

A chemical reaction is said to have occured when reactants react to form new products where the atoms undergo a change in bonding.

From the given reactions:

1. [tex]Zn+2HCl\rightarrow ZnCl_2+H_2[/tex]

Here Zn combines with hydrochloric acid to form zinc chloride and hydrogen.

2. [tex]H_2O+NaCl\rightarrow H_2O[/tex]

Here water remains as such as no new substance is formed.

3. [tex]Zn+Al+Cu\rightarrow Zn+Cu+Al[/tex]

Here no new substance is formed.

4. [tex]C_{12}H_{22}O_{11}+H_2O\rightarrow H_2O+C_{12}H_{22}O_{11}[/tex]

Here no new substance is formed.

Thus [tex]Zn+2HCl\rightarrow ZnCl_2+H_2[/tex] demonstrates an actual chemical reaction that forms a new substance

Answer:

hope this helps you!

Explanation:

Answer:

they arent alcohols.

Explanation:

Answer:

[tex]\Delta _{fus}H=332 \frac{J}{g}[/tex]

Explanation:

Hello!

In this case, since the heat of fusion of a solid substance stands for the energy required to melt it, which is a phase transition from solid to liquid, we can see that the heat lost by water is that gained by the solid, so we can write:

[tex]Q_{solid}=-Q_{w}[/tex]

Thus, by using the water data and its specific heat (4.184), we obtain:

[tex]Q_{solid}=-m_{w}C_{w}(T_f-T_i)\\\\Q_{solid}=-425g*4.184\frac{J}{g\°C}*(30.0-85.1)\°C\\\\ Q_{solid}=97,978.82J=98.0kJ[/tex]

Next, since the heat of fusion of a substance is usually represented in terms of energy per amount of substance, we use the mass of solid to obtain:

[tex]\Delta _{fus}H=\frac{98.0kJ}{295.5g}\\\\ \Delta _{fus}H=0.332\frac{kJ}{g}=332 \frac{J}{g}[/tex]

Best regards!

The heat of fusion of the solid is 0.332 KJ/g or 332 J/g

We'll begin by calculating the heat loss by the water. This can be obtained as follow:

Mass of water (M) = 425 g

Initial temperature of water (T₁) = 85.1 °C

Final temperature (T₂) = 30 °C

Change in temperature (ΔT) = T₂ – T₁ = 30 – 85.1 = –55.1 °C

Specific heat capacity of water (C) = 4.184 J/gºC

Q = MCΔT

Q = 425 × 4.184 × –55.1

Q = –97978.82 J

Divide by 1000 to express in KJ

Q = –97978.82 / 1000

Heat loss by water = –97.98 KJ

Heat gained by the solid (Q) = 97.98 KJ

Mass of solid (m) = 295.5 g

Q = m•Hf

97.98 = 295.5 × Hf

Divide both side by 295.5

Hf = 97.98 / 295.5

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Answer:

The correct answer is - (a) isobutene.

Explanation:

A 1° or primary hydrogen atom is one that is bonded to a 1° carbon atom; a 2° hydrogen atom is one that is connected to a 2° carbon atom; In isobutene only among all the all option having only primary hydrogen atoms. rest have secondary or teritary hydrogen atoms in them

C1∘H3≡CH: (only 1∘ hydrogen atoms)

Answer:

0.085 moles of  N₂O₅ are needed

Explanation:

Given data:

Mass of NO₂ produces = 7.90 g

Moles of N₂O₅ needed = ?

Solution:

2N₂O₅       →     4NO₂  + O₂

Number of moles of NO₂ produced :

Number of moles = mass/ molar mass

Number of moles = 7.90 g/ 46 g/mol

Number of moles = 0.17 mol

now we will compare the moles of NO₂   with N₂O₅.

                NO₂          :       N₂O₅

                  4            :          2

                0.17          :         2/4×0.17 = 0.085 mol

Thus, 0.085 moles of  N₂O₅ are needed.

Answer:

Mass = 6.538 g

Explanation:

Given data:

Mass of zinc hydroxide produced = 9.65 g

Mass of zinc required = ?

Solution:

Chemical equation:

Zn + 2MnO₂ + H₂O      →      Zn(OH)₂ + Mn₂O₃

Number of moles of zinc hydroxide:

Number of moles = mass/molar mass

Number of moles = 9.65 g/ 99.42 g/mol

Number of moles = 0.1 mol

now we will compare the moles of zinc and zinc hydroxide,

                  Zn(OH)₂           :          Zn

                       1                  :          1

                    0.1                  :         0.1

Mass of zinc required:

Mass = number of moles × molar mass

Mass = 0.1 mol × 65.38 g/mol

Mass = 6.538 g

Answer: 6.35

Explanation:

Answer:

Kp = P (N₂) . P³ (H₂)  /  P² (NH₃)

Explanation:

The reaction for the decomposition of ammonia is given by;

2NH₃ (g) ⇌ N₂ (g) + 3H₂ (g)

The pressure equilibrium constant gives the ratio of the pressure of the product over reactants for a reaction that is at equilibrium.

The pressures of the species are raised to the powers of their respective coefficients.

In this reaction;

Products =  N₂ (g) + 3H₂ (g)

Reactant = 2 NH₃ (g)

The pressure equilibrium constant (Kp) is given as;

Kp = P (N₂) . P³ (H₂)  /  P² (NH₃)

Answer:

The advantage of the globe is that it promotes visual accuracy. Students need to use a globe frequently if they are to form accurate mental maps. The advantage of the world map is that you can see the entire world at one time. The disadvantage is that world maps distort shape, size, distance, and direction.

Explanation:

miss girl- you could've just looked this up

(just make it look like you typed it)

Answer:

The advantage of the globe is that it promotes visual accuracy. Students need to use a globe frequently if they are to form accurate mental maps. The advantage of the world map is that you can see the entire world at one time. The disadvantage is that world maps distort shape, size, distance, and direction.

Friend?

Answer:

25% or 0.25 or 1/4

Explanation:

don't know which form you need so here you have all 3

good luck :)

Answer:

because it will help u

because it will make u to understand the question very well

Answer:

52.4%

Explanation:

Since a simple cubic unit cell contains only 1 atom. The packing efficiency of the simple cubic cell is 52.4 %

Answer:

There are  

4.517

⋅

10

23

atoms of Zn in 0.750 mols of Zn.

Explanation:

Since we know that there are  

6.022

⋅

10

23

atoms in every mole of a substance (Avogadro's Number), there are  

6.022

E

23

⋅

0.750

atoms of Zn in 0.750 mols of Zn.

Answer:

There are  4.517 ⋅ 10  23 atoms of Zn in 0.750 mols of Zn. have a good day:)

Explanation:

first we find the mass of the final solution

we know that

density=mass/volume

we know the density and volume

1=m/100

m=100g

now we calculate the mass ofNa2CO3

2% of 100 is equal with 2g of Na2CO3

Answer:

The negative charges of the surface will be attracted to the positive ends of the water molecule

Explanation:

A water molecule is a polar molecule. This means that the two ends of a water molecule are oppositely charged with one end being positive and the other end being negative.

When the positive end of a water molecule encounters a surface as shown in the attachment, where positive and negative charges are evenly distributed at rest, with the negative charges free to move, the negative charges will be attracted to the positive end of the water molecule due to the principle of electrostatics which states that unlike charges attract, while like charges repel. This means that negative and positive charges are attracted to each other while positive and positive or negative and negative charges are repelled from each other. Therefore, the water molecule will adhere to the surface because of the attraction between opposite charges.

The unlike charges will attract as expected based on the laws of electrostatics.

According to the laws of electrostatics, like charges repel while unlike charges attract. We are told in the question that water is a polar molecule with a positive and a negative end.

If the positive end of water dipole approaches the negative charges on the surface, the unlike charges will attract as expected based on the laws of electrostatics.

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Answer:

Volume required = 0.327 L

Explanation:

Given data:

Volume in L = ?

Molarity of solution = 1.772 M

Mass of BaCl₂ = 123 g

Solution:

First of all we will calculate the number of moles of BaCl₂,

Number of moles = mass/molar mass

Number of moles = 123 g/ 208.23 g/mol

Number of moles = 0.58 mol

Now, given problem will solve by using molarity formula.

Molarity = number of moles / volume in L

1.772 M = 0.58 mol / Volume in L

Volume in L = 0.58 mol  / 1.772 M

Volume in L = 0.327 L

Answer:

Unit of power is watt

Explanation:

Power = rate of doing work

or

Power, P = W/t

Where

W is work done and t is time

The unit of work done is Joules and that of time is seconds.

Power, P = J/s

We know that, J/s = watts

Hence, the unit of power is watts.

Answer:

pharynx > larynx>trachea> bronchi>alveoli   (so B)

Explanation:

nasal cavities (or oral cavity) > pharynx > trachea > primary bronchi (right & left) > secondary bronchi > tertiary bronchi > bronchioles > alveoli (site of gas exchange)