What is the atomic number of copper

Answer: D. the number of protons

Explanation: The number of protons shows you what the Atomic number of an element is on the Periodic table of elements.

The identity of an element is primarily determined by the number of protons it possesses. The Option C.

Each element on the periodic table has a unique number of protons in its nucleus which is referred to as its atomic number. This fundamental property of an element distinguishes it from other elements and determines its place on the periodic table.

While number of neutrons and electrons can vary within an element, it is the number of protons that defines its identity. Thus, the correct answer is C: the number of protons.

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Answer:

The accuracy of the measuring ruler is given as tenth of a centimetre and given that the image above the ruler is measuring in between a tenth of a centimetre, it is therefore measuring at a higher accuracy than the ruler

The least count of the vernier scale =  (Main scale's smallest reading)/(Number of vernier scale divisions)

Where;

Main scale's smallest reading = 0.1 cm

Number of vernier scale divisions = 10

We have;

The least count of the vernier scale =0.1/10 = 0.01

The image above the ruler, (the vernier scale measurement) should therefore measure at hundredth of a centimetre and the value of the measurement given to two places of decimal, 2.XX, as such 2.755 which is of a level of accuracy of a thousandth for the vernier scale would not be correct.

Explanation:

Answer:

Explanation:

                        N₂(g) + O₂(g) ⇄ 2NO( g )

We shall apply Le Chatelier's principle to see the effect of decrease in volume or increase in concentration on the effect of state of equilibrium in the reaction given .

In this reaction 1 volume of nitrogen gas reacts with 1 volume of oxygen to give 2 volume of NO gas . In total there is no change in volume due to reaction . So when we change the volume , the concentration of reactant and product will affect the rate of forward and reverse reaction . Overall there will be no change in the state of equilibrium . The equilibrium will neither shift to the right nor will shift to the left.

It will remain unchanged .

Answer:

ipotseeeeeeeeeeeeeeee

Answer:

Reacting hydrogen and oxygen gases to make water

Explanation:

Exothermic means that energy is released into the environment, so let's go through the process of elimination.

Allowing meat to thaw after taking it out of the freezer - NO it is endothermic, and takes energy/heat from the environment to thaw.

Popsicle melting on a warm summer day - NO also endothermic, the opposite of exothermic.

Boiling water in a beaker to convert it to steam - NO because we need to add heat, so it doesn't release any energy.

Rolling a ball up a hill - NO, for a ball to roll up a hill, it needs energy from something else, so it's not exothermic.

Reacting hydrogen and oxygen gases to make water - YES this reaction makes new bonds, which releases energy, so this is exothermic.

Among the following choices reacting hydrogen and oxygen gases to make water is an exothermic reaction as it releases energy as new bonds are formed.

An exothermic reaction is defined as a chemical reaction which involves release of energy in the form of light,heat .In these reactions, energy is transferred from system to surroundings rather than taking energy from surroundings into system as in endothermic reactions.

In an exothermic reaction,change in enthalpy is negative.Therefore, it can be inferred that net amount of energy which is required to start the exothermic reaction is less than the net amount which is released by the reaction.

Examples of exothermic reactions are combustion reactions, detonation of nitroglycerin , neutralization reactions and nuclear fission.

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Answer:

[tex]\large \boxed{350}[/tex]

Explanation:

In multiplication and division problems, the answer can have no more significant figures than the number with the fewest significant figures.

My calculator gives the result:

[tex]\dfrac{4568}{13} = 351.3846154[/tex]

4658 has four significant figures.

     13 has two significant figures.

You must round to two significant figures.

That is, you drop all the digits to the right of the 5 — the red line in Fig. 1 below. You are rounding to the nearest ten.

To round a number to the nearest ten, you look at the number in the ones place (1). See Fig. 2.

If the number to be dropped — the digit in the ones place — is less than 5, you drop the digit in the ones place (Fig. 3). It becomes a zero.

The number in the tens place is a trailing zero. It is not significant.

[tex]\text{The quotient of $\dfrac{4658}{13}$ is $\large \boxed{\mathbf{350}}$}[/tex]

Answer:

0.60 mL

Explanation:

1. Set up the equation using Vi = MfVf / Mi

Vi = (1.5M · 1L) / 2.5M

2. Solve

1.5 / 2.5 = 0.6

Answer:

True

Explanation:

This is true because no chemical bonding or change was involved only mechanical mixing.

Answer:

the atomic number of a neon is 10

Answer:

[tex]\huge\boxed{\sf D = 7.8 \ g/cm^3}[/tex]

Explanation:

Density = Mass / Volume

Where Mass = 39 g and Volume = 5 cm³

So,

[tex]\sf Density = \frac{39}{5} \\Density = 7.8 g/cm^3[/tex]

Answer:

Here is it....

Explanation:

Answer:

The shape of a molecule based on the number of electron pairs on the valence shell of its central atom

Explanation:

The improvement of the Sidgwick-Powell theory came to be known as the Valence Shell Electron Pair Repulsion theory (VSEPR). This theory approaches the determination of molecular shape from the perspective of the number of electron pairs on the valence shell of the central atom in the molecule.

Electron pairs on the valence shells of atoms leads to repulsion. Repulsion between two lone pairs is greater than repulsion between a lone pair and a bond pair which is also greater than repulsion between two bond pairs.

Lone pairs cause more repulsion, hence they distort molecules from the ideal shape predicted based on their electron domain geometry.

The percentage of carbon in urea is [CO(NH 2) 2] is 20%

Explanation:

the first question's answer is a

the second question's answer is c

Answer:

Answer:

The answer is "6.68 [tex]\frac{ml} {hr}[/tex]".

Explanation:

It's going to be 18.18 kg to turn body mass to kg.  

Size 1mg / kg / hr, therefore = 1 x 18.18

                                               = 18.18 kg / hr  

now we adding 30 mg / ml of dextrose = 30 x 15

                                                                 [tex]=\frac{450mg}{15 ml +150 ml}[/tex]

of dextrose, from 15 ml to 150 ml;  

Therefore, now 450 mg in 165m:    

[tex]= \frac{ 450}{165}\\ \\=2.72 \frac{mg} {ml}[/tex]  

now divide the   18.18 by 2.72:

[tex]=\frac{18.18}{2.72}[/tex]

= 6.68 [tex]\frac{ml} {hr}[/tex]

Answer:

If mass remains the same while the volume of a substance changes, the density of the substance will also change.

Answer:

BELOW

Explanation:

If mass remains the same while the volume of a substance decreases the density of the substance will increase.

Answer:

Diamonds

Explanation:

The melting point of sugar is 186C

The melting point of oxygen is -218C

The melting point of diamonds are 4078C

Therefore diamonds have the highest melting point.

You can also think of their structures, as diamonds have a covalent network structure, meaning they are really strong and have a high melting point

Oxygen has a covalent molecular structure

Sugar has a much weaker covalent network structure

Answer:

Explanation:

The density of an object can be found using the formula

From the question

mass of kerosene = 36.4 g

volume of kerosene = 45.6 mL

To find the density substitute the values into the above formula and solve

We have

= 0.7982

We have the final answer as

Hope this helps you

Answer: 0.01 moles (I am guessing)

Explanation:

Firstly, cm3 and ml are equal to one another, therefore 250cm3 can also be written as 250 ml. I Googled and found that ideally, one mole of gas will occupy a volume of 22.4 L (22,400 ml) at s.t.p. 250 ml out of 22,400 ml is 0.01 rounded, therefore I assume that is the answer. About 0.01 mole occupies 250 cm3 at s.t.p.

Answer:

The proportionality constant ( Henry’s constant) = 2.32 * 10^-5 M/kPa

Explanation:

Here in this question, we are concerned with calculating the proportionality constant for this gas.

Mathematically, we can get this from Henry law

From Henry law;

Concentration = Henry constant * partial pressure

Thus Henry constant = concentration/partial pressure

Henry constant = 0.00290 M/125 kPa = 2.32 * 10^-5 M/kPa

Answer:

The pH of 500 cm³, 0.2 mol/dm³, Ca(OH₂) is ≈ 13.6

Explanation:

The given parameters are;

Concentration of the calcium hydroxide, Ca(OH₂) = 0.2 mol/dm³

Volume of the calcium hydroxide, Ca(OH₂) = 500 cm³

Given that the calcium hydroxide, Ca(OH₂),  undergoes complete ionization in water, complete dissociation, we have;

Ca(OH₂)  ⇄  Ca²⁺ + 2 OH⁻

Therefore, we have;

2 moles of [OH⁻] for each mole of Ca(OH₂) which gives the concentration of  [OH⁻] as

[OH⁻] = 2 × 0.2 ≈ 0.4 mol/dm³

The pH is given by the formula

pH = 14 + ㏒₁₀ [OH⁻]

pH = 14 + ㏒₁₀ (0.4) = 14 - 0.3979 = 13.6021 ≈ 13.6

The pH of the 500 cm³ 0.2 mol/dm³ Ca(OH₂) ≈ 13.6.

Answer:

ZnC4H10

Explanation:

The empirical formula of a compound refers to the formula that gives the simplest whole number ratio of each atoms of the elements in the compound.

The empirical formula is calculated thus:

The given percentages in the question represent the mass in grams of each element in the compound.

Zinc= 53%, C= 38.9%, H= 8.1% which represents 53g, 38.9g and 8.1g of each element respectively.

Molar Mass of Zn= 65.4 g/mol

Molar Mass of C= 12 g/mol

Molar Mass of H= 1 g/mol

Step 1: Divide the mass of each element by the molar mass given to convert to moles:

Zn= 53/65.4 = 0.81moles

C= 38.9/12 = 3.24moles

H= 8.1/1 = 8.1moles

Step 2: Divide each mole value by the smallest number of moles calculated, which is 0.81moles:

Zn= 0.81/0.81 = 1

C= 3.24/0.81 = 4

H= 8.1/0.81= 10

This is the mole ratio represented in the subscript of each element in the empirical formula:

That is, Zn (1) C (4) H (10)

Empirical formula= ZnC4H10

Answer:

Hi there!!!

The answer is given in picture.

In question we had 2 sodium(Na) and chlorine (cl) but after reaction nacl donot contain it. so, we need to put 2 infront of nacl to make them equal.

As balancing chemical equation refers to the process of keeping or making equal to the atoms of both product and reactant.

Hope it helps..

Answer:

These are two types of indicators which show a solution is either an acid a natural or an alkali solution

Explanation:

Hope this helps :)

Answer:

a 1) XZ2

2) YZ

3) X2

b 1) Ionic bond

2) Ionic bond

3) covalent bond

c) ionic compounds has high melting and boiling point

ionic compounds can conduct electicity in aqueous form

covalent compounds have electrons shared between the atoms

covalent compounds have lower melting point compared to ionic compound

Answer:

(i) XZ = Potassium Sulfide [K2SO4]

(ii) YZ = Potassium Chloride [KCI]

(iii) X = Sulfur [S]

b) (i) Ionic Bond. (ii) Ionic Bond. (iii) Covalent Bond.

c) (i) Ionic compounds have high melting and boiling points.

(ii) Ionic compounds can conduct electricity in a molten state or a solution as they have ions that can move and carry charge.

(iii) Covalent compounds have low melting and boiling points.

(iv) Covalent compounds can not conduct electricity as all electrons are involved in bonding so there are no free electrons or ions to carry the charge.

Hope this is OK :))

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Answer:

C. Partial charges in water molecules attract the charges in the atoms of the ionic crystal, pulling the atoms off the crystal.

Explanation:

Water consists of partial positive and hydrogen ions and partial negative oxygen ions. The ionic crystals also dissociate into ions when in water.These partial charges and ability of ionic compounds to dissociate in water are the main reason why ionic crystals dissolve in water.

The partial charges in the water molecules form a strong attraction towards the charges in the atoms of ionic crystals. This then pulls the atoms from the crystals and ends up in the dissolution of the ionic crystals.

Answer: 89.57 %

Hope it helps