In the image above the ruler is measuring in centimeters. The blue cylinder falls somewhere between 2.7cm and 2.8cm according to the ruler. Since we can estimate the last digit I would say that the length of the cylinder is 2.76cm. Since I am estimating any number 2.72cm or 2.78cm could also be correct.

Why would 2.755 not be a correct measurement according to estimating the last digit?

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:

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:

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:

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:

+VE

Explanation:

If we look at the reaction profile pictured in the question, we can easily identify A as the enthalpy of the reaction. The enthalpy of reaction (ΔHrxn) is usually defined as the difference between the total enthalpy (heat content) of the products of a reaction and the total enthalpy (heat content) of the reactants in that reaction.

Looking at the figure, we can see that the enthalpy of products is greater than the enthalpy of reactants, hence ∆Hrxn is positive as stated in the answer above.

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:

Answer:here is it...

Explanation:

The question tag for the statement "Lynne speaks French and German" would be "doesn't she?"

The question tag is a short question added to the end of a statement to turn it into a question and seek confirmation or agreement. It is usually formed by using an auxiliary verb opposite in polarity to the main verb in the statement.

In the given statement, "Lynne speaks French and German," the main verb is "speaks." Since the main verb is in the affirmative form, the question tag should use the negative form.

Therefore, we use the auxiliary verb "doesn't" (the negative form of "does") and add the pronoun "she" to match the subject of the statement.

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Answer:

C. size; direction

Explanation:

By definition, a machine is referred to any device that makes work easier. It takes force to do work, hence, work refers to the application of force over a particular distance. A machine aims at making the work easy by changing how it is done. Simple machines, which include: levers, pulleys, inclined planes etc. all carry out the same thing, which is to make work easier, by changing the size/magnitude and direction of the applied force.

A simple machine tends to change the size of the inputted force by increasing it over a shorter distance. The machine increases the force applied better than it can be done manually e.g. a plier and nutcracker increases/changes the applied force better than it can be done with bare hands.

Also, a simple machine can achieve making work easier by changing the direction at which the force is applied. The machine applies the force on the object in an opposite direction or contrary to the way it was manually applied.

Answer:

Hope it helps!!!

............

In the Lewis structure, the Ca atom donates its two valence electrons to two F atoms.

The bonding in calcium fluoride (CaF₂) involves the transfer of electrons from calcium (Ca) to fluorine (F), resulting in the formation of ionic bonds.

Each F atom gains one electron to achieve a stable electron configuration of eight electrons in its outermost energy level. The electrostatic attraction between the positively charged Ca ion (Ca²⁺) and the negatively charged F ions (F⁻) holds the compound together.

It's important to note that the diagram represents a simplified 2-dimensional representation of the compound's structure. In reality, the compound adopts a three-dimensional crystal lattice structure, with each Ca ion surrounded by eight F ions and each F ion surrounded by four Ca ions.

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Answer:

12,375 cm³

Explanation:

v=l×w×h

Since there are 3 books the equation would then be

v=3(l×w×h)

v=3(25×15×11)

v=3(4,125)

v=12,375 cm³

Answer:

graphite

Explanation:

Graphite is opaque, a very good lubricant, a good conductor of electricity, and a thermal insulator. Allotropes of carbon are not limited to diamond and graphite, but also include buckyballs (fullerenes), amorphous carbon, glassy carbon, carbon nanofoam, nanotubes, and others.

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Answer:

Solids do not undergo diffusion because it has a fixed structure (vibrates in a fixed position) and it also cannot be compressed.

Hoped this helped in any way

Have a nice day

Answer:

Option B

Explanation:

Let us go through each of the options individually.

option A.

he phases in a chemical reaction tell us the state of the reactants and the products.

This is true because phases representations such as s, l , g and q tells us the state of the reactants if they are in the solid or liquid or gaseous or aqueous state of matter respectively. So this is not our answer.

option B

An individual coefficient, with no reactant or product, in a balanced equation is meaningless.

This option is correct, because in every reaction, there must be the reactant and product present.

option C

The subscripts in a balanced equation tell us the number of atoms in a molecule.

This is correct. Consider the equation below;

2H₂ + O₂ --> 2H₂O

In the reactant phase, the subscripts tells us that we have just two atoms of oxygen present.

Answer:

hexagonal layers slide

Explanation:

The layers in graphite can slide over each other because the forces between them are weak. The delocalised electrons are free to move through the structure, so graphite can conduct electricity.This makes graphite slippery, so it is useful as a lubricant .

i think it's right

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Answer:

The baseball is thrown twice as fast as the softball in the same direction.

Explanation:

Answer:

4-phospho,Bromooctane

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

It causes freezing point depression which requires the gasoline to reach a much lower temperature before freezing. Hence, option C is correct.

Whenever a solute is added to a solution/solvent, it leads to depression in the freezing point of that solution/solvent. Depression in the freezing point of a solution on the addition of a solute is a colligative property.

A colligative property is a physical property which depends upon the number of solutes added not on the nature of solutes which means it does not matter whether we are adding 1000 particles of sugar or salt in water, the depression in the freezing point will occur by the same °C. Also, the more a solute is added the more will be the depression at the freezing point.

The formula for depression at the freezing point is mentioned as under:

             Δ T = K x m

where Δ T = freezing point depression;

                 K = cryoscopic constant;

                 m = molality of the solution.

For example, The freezing point of water is 0 °C but as soon as we add a 92 gm solute like NaCl (common salt) in 1000 gm of water, its freezing point will be lower to −3.72 °C.

Hence, option C is correct.

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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:

rabbit

Explanation:

Answer:

rabbit

Explanation:

the rabbit is the consumer because the sun "produces" the tree and mushroom, the rabbit comes along and eats the mushroom which was produced by the sun.

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.

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

Explanation:

the first question's answer is a

the second question's answer is c

One mole of H₂S gas contains 6.022 × 10²³ H₂S molecules. Hence, 2.50 mol of H₂S contains 1.50 × 10²⁴ molecules. Thus, option A is correct.

Any substance containing 6.022 × 10²³ number of atoms is called one mole of that substance. This number is called Avogadro number. Thus, one mole every elements contains Avogadro number of atoms.

Similarly a compound is made of molecules. One mole of a compound contains 6.022 × 10²³ number of molecules. The mass of a compound with Avogadro number of molecules is called its molar mass.

As any other compound, one mole of H₂S contains 6.022 × 10²³ molecules. Therefore, the number of molecules in 2.50 moles of H₂S is :

2.50 moles × 6.022 × 10²³ molecules/mol =  1.50 × 10²⁴molecules

Hence, the number of molecules present in 2.50 moles of H₂S is  1.50 × 10²⁴.

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Answer:

Explanation:

Sn + 2HBr =  SnBr₂ + H₂

Here HBr is an acid but Sn is not a base . It is a metal . So it is not an acid - base reaction .

HCl + KOH =  KCl + H₂O

HCl is an acid and KOH is a base so it is an acid base reaction.

2AlCl₃ + 3Ca(OH)₂ =  2Al(OH)₃ + 3CaCl₂

It is an acid base reaction . It is so because aluminium hydroxide is a lewis acid and calcium hydroxide is a base . So it is an acid base reaction .

2C₂H₆ +7O₂ =  4CO₂ + 6H₂O

It is not an acid base reaction . It is actually an example of oxidation reaction in which ethane burns in oxygen to give carbon dioxide and water.

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