An atom of nitrogen has seven electrons. Which diagram correctly represents the arrangement of these electrons?
ОА.
OB
1112
1s 11:28 1111
2p
1s 12
2p
1s 12
12s 2p
OD. 1111s 112s
112p
Ос.

Answer:

Anna didn't wear a lab coat

Explanation:

The first thing anyone who is to carry out a procedure or an experiment in a lab needs to do when he/she enters a lab is to wear a lab coat. This is a lab safety rule that protects the individual from been affected by spillage that could occur as a result of the experiment been conducted.

From the narration in the question, it is not stated anywhere that Anna wore a lab coat before embarking on her lab procedure.

Answer:

C, wear goggles, anytime chemicals, heat, or glassware are used.

Explanation:

This is the correct answer on the Lincoln learning platform.

Complete Question:

In ∆ABC, if sin A = 4/5 and tan A = 4/3, then what is cos A?

Answer:

[tex]cos A= \frac{3}{5}[/tex]

Explanation:

Given

[tex]sin A = 4/5[/tex]

[tex]tan A = 4/3[/tex]

Required

[tex]cos A[/tex]

In trigonometry;

[tex]tanA = \frac{sinA}{cosA}[/tex]

Multiply both sides by cosA

[tex]cos A * tanA = \frac{sinA}{cosA} * cos A[/tex]

[tex]cos A * tanA = sinA[/tex]

Divide both sides by tanA

[tex]\frac{cos A * tanA}{tanA} = \frac{sinA}{tanA}[/tex]

[tex]cos A= \frac{sinA}{tanA}[/tex]

Substitute values for sinA and tanA

[tex]cos A= \frac{4/5}{4/3}[/tex]

[tex]cos A= \frac{4}{5} / \frac{4}{3}[/tex]

[tex]cos A= \frac{4}{5} * \frac{3}{4}[/tex]

[tex]cos A= \frac{4 * 3}{5 * 4}[/tex]

[tex]cos A= \frac{3}{5}[/tex]

[tex]1.44\times 10^{-2}[/tex]

Explanation:

We need to find the value of [tex]3.49\times 10^{-3}+1.1\times 10^{-2}[/tex].

Here,

The first number is [tex]3.49\times 10^{-3}[/tex]

The second number is [tex]1.1\times 10^{-2}[/tex]

To add these numbers as follows :

[tex]3.49\times 10^{-3}+1.1\times 10^{-2}=0.01449\\\\=1.44\times 10^{-2}[/tex]

So, the value of [tex]3.49\times 10^{-3}+1.1\times 10^{-2}[/tex] is [tex]1.44\times 10^{-2}[/tex]

Answer:

B. Cutting the supplies of oxygen

Answer:

An ionic bond is a chemical bonding involving the attraction between oppositely charged ions

Explanation:

On the periodic table, elements from group 1 and 7 are attracted to each other and when they bond, it's called ionic bonding. This is because of their valence electrons and ions.

Answer:

Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds. It is one of the main types of bonding along with covalent bonding.

Answer:

The answer that completes the question are in BOLD:

At chemical equilibrium, the amount of PRODUCT AND REACTANT REMAIN CONSTANT because the RATES OF THE FORWARD AND REVERSE REACTIONS ARE EQUAL.

Explanation:

In a reversible chemical reaction, an equilibrium is said to be achieved when the rates of the forward reaction is equal to that of the reverse reaction. A reversible reaction is one in which products are formed from reactants simultaneously with the formation of reactants from products.

The combination of two or more substances called REACTANTS gives rise to another substance called PRODUCT, which can in turn give rise to Reactants again. With time, the rate at which the reactants give rise the products, which is called the FORWARD REACTION will be equal to the rate at which the products give rise to the reactants, which is called REVERSE REACTION. At this point, the chemical reaction is said to be in a STATE OF EQUILIBRIUM.

When the rate at which both reaction occurs becomes equal i.e. at an equilibrium state, the concentration of both the reactants and the products becomes constant i.e. no longer changes. Hence, the amount of the reactants forming the products is the same as the amount of products forming the reactants.

N.B: At chemical equilibrium, the amount of the reactants and products does not necessarily equals zero (0). It simply means that there is no net change in the concentration/amount of both reactants and products.

Answer:

This is called a chemical reaction. gas may form.heat may be produced and the color may change

Answer:

Benzene

Explanation:

You have to find the freezing point for each of these (make sure they're in Celsius). You might want to double check these but:

Benzene: 5.5

Water: 0

Butane: -138

Nitrogen: -210

The substances that will solidify before the temperature reaches 0°C is benzene. The correct option is A.

Freezing, also known as solidification, is a phase transition that occurs when the temperature of a liquid falls below its freezing point.

If the intermolecular forces between its molecules are strong, the freezing point is high.

When the forces are weak, the freezing point is low. The freezing point of a liquid or the melting point of a solid occurs when the solid and liquid phases are in equilibrium.

Pure benzene has a freezing point of 5.48 degrees Celsius. Because of the salt in it, fresh water freezes at 32 degrees Fahrenheit, but seawater freezes at around 28.4 degrees Fahrenheit.

Thus, as per the given scenario, the correct option is A.

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Answer:

Matching

6.D

7.A

8.C

9.B

Explanation:

Took test

103 °C, 90 °C, 101 °C Neither accurate nor precise, 100 °C, 99 °C, 100 °C are Precise, 105 °C, 106 °C, 105 °C are Both accurate and precise, 99 °C, 101 °C, 100 °C are Accurate. These are the correct set of measurements of the boiling point of water.

The melting point is defined as the temperature at which solid and liquid phases are at equilibrium state, whereas the boiling point is defined as the temperature at which the pressure of a vapor of a  liquid is equal to the external pressure.

Melting point in which the melting of solid occur to become a liquid at a given temperature, here the molecules gain enough amount of kinetic energy to get the intermolecular forces to convert into another form.

In case of Boiling point the liquid phase enters into the gaseous phase, when the external pressure is high than a temperature for the vapor pressure equal to the external pressure.

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Answer:

Answer:

Potassium  (K)

Sodium  (Na)    

Calcium  (Ca)

Magnesium (Mg)  

Aluminium  (Al)

Iron  (Fe)  

Lead  (Pb)

Copper  (Cu)  

Silver  (Ag)

Gold  (Au)

Answer: 1. Sodium Benzoate

Explanation: An anti-oxidant is a substance that can help prevent or stop the damage done by free radicals. Examples include; Sulphur Dioxide, Sulphite Salts, Citric Acid, e.t.c

Sodium benzoate is a pure preservative.

Answer:

[tex]\boxed{\sf{view \ explanation}}[/tex]

Explanation:

Compound definition:

A compound is a chemical substance formed by two or more chemically bonded elements.

Three compounds:

Water is a compound with the formula [tex]\sf H_2O[/tex].

Two hydrogen atoms and one oxygen atom is present in one molecule of water.

Sodium chloride or table salt is a compound with the formula [tex]\sf NaCl[/tex].

One sodium atom and one chlorine atom is present in one molecule of sodium chloride.

Ammonia is a compound with the formula [tex]\sf NH_3[/tex].

In one molecule of ammonia, one nitrogen atom and three hydrogen atoms are present.

Answer:

See below

Explanation:

Three compounds are:

1) [tex]\mathrm {H_{2}SO{4}}[/tex] [Sulfuric acid]

The elements in this compound are hydrogen (H) , Sulfur (S) and Oxygen (O).

2) [tex]\mathrm {NaOH}[/tex] [Sodium hydroxide]

The elements in this compound are Sodium (Na) , Oxygen (O) and Hydrogen (H).

3) [tex]\mathrm {HCl}[/tex] [Hydrochloric acid]

The elements are Hydrogen (H) and Chlorine (Cl).

Answer:

Group number – 8

Explanation:

To determine the charge on the ion formed by various elements, we simply consider their valence electrons.

However, this is only applicable to elements in group 1, 2 and 3 only.

To determine the charge on the ions formed by non metals i.e elements in group 4, 5, 6, 7 and 8(group 0) we simply subtract 8 from the group number i.e group number – 8

This can be further explained as follow:

Chlorine belong to group 7 because it has 7 valence electrons.

The charge on the chloride ion can be obtained as follow:

Group number = 7

Charge on ion =?

Charge on ion = Group number – 8

Charge on ion = 7 – 8

Charge on ion = – 1

Therefore, the charge on chloride ion is – 1.

Answer:

It is noticed that after five days, there is elongation of the root cells in the roots of onion in the jam bottle

Explanation:

It is noticed that after five days, there is elongation of the root cells in the roots of onion in the jam bottle. The growth of a plant is due to the availability of the growing and  dividing cells in the meristematic regions of the apical meristems. (stem cells). This site are active site for elongation and differentiation  of the stem tissues. In the apical meristem of the root cells, the cells have the potential to carry out mitosis and cell division repeatedly in order to generate newer cells for extension and development of stems and leaves. With each cell division, one cell remains in the meristem which the other increases in size and differentiate due to different genomic expression to form the meristem regions which eventually becomes the stem structure.

Answer:examples for neutralization - treating indigestion,treatment for insect bites.hope it help you

Explanation:

Answer:

1.5g/cm³

Explanation:

density=mass÷volume

mass= 1.5kg (change into g) = 1500g

volume of the cube = 10×10×10 = 1000cm³

density= divide 1500g÷1000cm = 1.5g/cm³

YOUR WELCOME!

The density of the cube on Earth that weighs 1.5 kg and has a side length of 10 cm is 1.5g/cm³

"Density is the mass per unit volume. Density is a scalar quantity. It is denoted by d and the symbol for density is given as rho, a Greek symbol. Density is calculated as mass divided by volume."

density = mass / volume

The mass of the cube on earth is 1.5 kg

The side length of the cube is 10 cm.

The mass is given in kg. It is converted into grams.

mass= 1.5kg (change into g) = 1500g

A cube is a three-dimensional square, it has 6 faces, so its volume will be calculated completely.

Volume of the cube = 10×10×10 = 1000cm³

Putting the values in the formula of density

density= divide 1500g /1000cm = 1.5g/cm³

Thus, the density of the cube on Earth is 1.5g/cm³.

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Answer:

The specific heat of the metal is 0.0482 joules per gram-Celsius.

Explanation:

Block of metal is cooled by adding water and thermal equilibrium is reached. According to the First Law of Thermodynamics and by supposing the absence of energy and mass interaction of the system with surroundings, the change in the energy of the system is represented by:

[tex]\Delta U_{m} + \Delta U_{w} = 0[/tex]

Where [tex]\Delta U_{m}[/tex] and [tex]\Delta U_{w}[/tex] are the changes in internal energies of the block of metal and water, measured in joules.

The expression described above is now extended by applying the definition of internal energy for constant mass systems:

[tex]m_{m}\cdot c_{v,m}\cdot (T_{m,in}-T_{m,out}) + m_{w}\cdot c_{v,w}\cdot (T_{w,in}-T_{w,out})= 0[/tex]

Where:

[tex]m_{m}[/tex], [tex]m_{w}[/tex] - Masses of the block of metal and water, measured in grams.

[tex]c_{v,m}[/tex], [tex]c_{v,w}[/tex] - Specific heats of the block of metal and water, measured in joules per gram-Celsius.

[tex]T_{in, m}[/tex], [tex]T_{in, w}[/tex] - Initial temperatures of the block of metal and water, measured in Celsius.

[tex]T_{out, m}[/tex], [tex]T_{out, w}[/tex] - Final temperatures of the block of metal and water, measured in Celsius.

The specific heat of the metal is cleared in the equation:

[tex]c_{v,m} = -\frac{m_{w}\cdot c_{v,w} (T_{w,in}-T_{w,out})}{m_{m}\cdot (T_{m,in}-T_{m,out})}[/tex]

If [tex]m_{m} = 12.6\,g[/tex], [tex]m_{w} = 100\,g[/tex], [tex]c_{v,w} = 4,186\,\frac{J}{kg\cdot ^{\circ}C}[/tex], [tex]T_{w,in} = 21\,^{\circ}C[/tex], [tex]T_{m,in} = 94\,^{\circ}C[/tex] and [tex]T_{m,out} = T_{w,out} = 25.1\,^{\circ}C[/tex], the specific heat of the metal is:

[tex]c_{v,m} = -\frac{(100\,g)\cdot \left(4,186\,\frac{J}{g\cdot ^{\circ}C} \right)\cdot (25\,^{\circ}C-25.1\,^{\circ}C)}{(12.6\,g)\cdot (94\,^{\circ}C-25.1\,^{\circ}C)}[/tex]

[tex]c_{v,m} = 0.0482\,\frac{J}{kg\cdot ^{\circ}C}[/tex]

The specific heat of the metal is 0.0482 joules per gram-Celsius.

Answer:

iii. 3 moles of A react with 2 moles of B to form 1 mole of A 3B 2

Explanation:

A + 2 B → A 3B 2

A chemical equation among other things, gives the stoichiometry of the reaction; that is the relationship between reactants and products.

This relationship is basically stated in moles form the coefficients of the reactants and product.

From the reaction above, we can say;

1 mol of A reacts with 2 mol of B to form 1 mol of A3B2

It cannot be grams because the reactants and products all have different molar masses.

The correct interpretation of the equation of the hypothetical chemical reaction is; Choice (iii) 3 moles of A react with 2 moles of B to form 1 mole of A 3B 2.

Definition:

Chemical equations are equations that make use of chemical formulae and symbols to represent chemical reactions. The left-hand side of a chemical equation represents the reactants and the right-hand side represents the products.

Each reacting entity is also assigned its corresponding stoichiometric coefficient.

However, this stoichiometric coefficient is to quantify the no. of moles of the reactants consumed or products formed as the case may be.

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Answer:

It loses kinetic energy.

Explanation:

The definition of heat is molecules moving fast, so it cooling would mean they slow down.

Answer:

B, It loses kinetic energy.

Explanation:

Hey there !

Mass = 237 g

Volume 237 mL

Therefore:

Density = mass / Volume

D = 237 / 237

D = 1.0 g/mL

Hope this helps!

Q = m.c.AT

m = 50,0 g of iron

c = 0.450 J.g-1°C-1

AT = 10°C

Thus

Q = 50 * 0.450 * 10

Q = 225 J

Is the heat energy

Hope it helps xx

Answer:

Alpha decay is a type of radioactive disintegration in which unstable atomic nucleus releases a helium nucleus or alpha particle and transform into a different element. The new element formed will be reduced by four and the atomic number will be reduced by two.

Example of alpha decay is: Uranium 238 transform into Thorium 234 with the emission of an alpha particle.

Answer:

6.79 atm

Explanation:

Applying Dalton's law of partial pressure:

[tex]P_{total} = P_{helium} + P_{oxygen}[/tex], where [tex]P_{total}[/tex] = total partial pressure of all the component gases in the mixture, [tex]P_{helium}[/tex] = partial pressure of helium gas, and [tex]P_{oxygen}[/tex] = partial pressure of oxygen gas.

From the illustration, [tex]P_{total}[/tex] = 7.00 atm and [tex]P_{oxygen}[/tex] = 0.21 atm. Hence, the partial pressure due to helium is calculated such that:

[tex]P_{helium}[/tex] = [tex]P_{total} - P_{oxygen}[/tex]

           = 7.00 - 0.21

              = 6.79 atm

Therefore, the partial pressure due to helium in order to maintain the pressure due to oxygen at 0.21 atm would be 6.79 atm.

Answer:

if an atom gains an electron, the ion has negetive charge

Answer:

A scientific hypothesis must meet 2 requirements:

Explanation:

A scientific hypothesis must be testable, and;

A scientific hypothesis must be falsifiable.

Answer:

≈ 0.70 g/cm³ (answer rounded up to 2 decimal places)

Explanation:

The mass of empty cylinder is 20g

The mass of water filling the cylinder = 30g - 20g = 10g

The mass of unknown liquid filling the cylinder = 27g - 20g = 7g

Density of water = 997 kg/m³

Converting this density to g/cm³ we get;

1kg = 1000g , 1m³ = 1000000cm³

So density = [tex]\frac{997000}{1000000}[/tex] g/cm³ = 0.997 g/cm³

So the volume of water occupied by 10g is;

10 × 0.997 = 9.97 cm³

This volume is also occupied by 7g of the unknown liquid.

Density = mass/volume

Density of the unknown liquid = 7g ÷ 9.97cm³ = 0.702106319 g/cm³ ≈ 0.70 g/cm³ (answer rounded up to 2 decimal places)

Answer:

The volume of ozone produced is 7.53 L.

Explanation:

The reaction is:

3O₂(g)  →  2O₃(g)   (1)      

0.477 mol   V=?

11.3 L    

From the reaction (1) we have that 3 moles of O₂ produce 2 moles of O₃ so the volume of the ozone produced can be calculated as follows:

[tex] V_{O_{3}} = V_{O_{2}}*\frac{n_{O_{3}}}{n_{O_{2}}} = 11.3 L*\frac{2}{3} = 7.53 L [/tex]

Therefore, the volume of ozone produced is 7.53 L.

I hope it helps you!

The ozone volume (in liters) is 7.53 L.

The volume of the ozone in liters should be

[tex]= 11.3 \times 2\div 3[/tex]

= 7.53L

we have that 3 moles of O₂ produce 2 moles of O₃

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Answer:

Mg2+

Explanation:

o2- =2,8

mg2+ =2,8

na+ =2,8

f- =2,8

since they are all same it depends on protons.

mg2+ has least protons