Which of the following happens during an endothermic chemical change?

Heat is absorbed.
Heat is released.
Net energy decreases.
Net energy remains constant.

Answer:

Answer is: elements in the same group have similar chemical properties. Periodic law is the arrangement of the elements in order of increasing atomic number.

Answer:

B. Protons and Neutrons

Answer:

Option"B" is correct.

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Answer:

100 times more acidic.

Explanation:

If you look at the pH scale, pH2 is 2 "jumps" away from pH4, therefore, pH2 is 100x more acidic than pH4.

Answer:

Metals on the left of the Periodic Table.

Non-Metals on the top-right, plus Hydrogen.

Answer:

i is the correct answer.

Explanation:

the RAM of aluminum is indeed 27. And since the RAM of substances are measured in terms of the C-12 isotope then R indeed explains why the RAM Al is 27.

Answer:

because the load arm is greater than the effort arm. As we know that when the load arm is greater than the effort arm, the mechanical advantage will always be lesser than one, which results in gain in speed

On changing the ratio of baking soda and vinegar changes the amount of carbon dioxide produced is true, because each species will depends on both reactants.

Chemical reaction between baking soda and vinegar is shown below in the attached image in which the formation of carbon dioxide, water and sodium acetate takes place. So the formation of carbon dioxide depends on the baking soda and baking soda reacts with vinegar to form sodium acetate so change in the ratio will changes the amount of carbon dioxide.

Hence on changing the ratio of reactants and vinegar changes the amount of carbon dioxide.

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Answer:

In a physical change the appearance or form of the matter changes but the kind of matter in the substance does not. However in a chemical change, the kind of matter changes and at least one new substance with new properties is formed.

Answer:

Explanation:

Put the given unit on the bottom of the brackets.

84 miles [tex]\frac{1 km}{0.6 miles}[/tex] = 84/0.6 = 140 km

Answer:

a. CH2(NH2)COOH

[tex]molecular \: mass = (12 \times 2) + (5 \times 1) + (14 \times 1) + (16 \times 2) \\ = 24 + 5 + 14 + 32 \\ = 75 \: grams[/tex]

b. H2SO4

[tex]molecular \: mass = (2 \times 1) + 32 + (16 \times 4) \\ = 2 + 32 + 64\\ = 98 \: grams[/tex]

Answer:

so i think physical change

Answer:

hexane

Explanation:

This is a 6- carbon hydrocarbon with no multiple bonds or any functional groups (such as -OH). Thus, the prefix 'hex' refers to the 6 carbons and 'ane' refers to the molecule being an alkane.

Naming molecules:

Number of carbons

• pentane: 5 carbons

• hexane: 6 carbons

• heptane: 7 carbons

• octane: 8 carbons

• nonane: 9 carbons

Functional groups (for 6- carbons molecules)

• Alkene (C=C): hexene

• Alcohol (-OH): hexanol

• Alkyne (C≡C): hexyne

Answer:

7.2

Explanation:

you first have to find the number of moles of nitrogen dioxide by using the number of moles for calcium nitrate and the mole to mole ratios

number of moles of calcium nitrate=mass/mm

=16.4/102

=0.16g/mol

then you use the mole to mole ratios

2 : 4

0.16: x

2x/2=0.64/2

x=0.32g/moles of nitrogen dioxide

then you use the formula for the volume

v=22.4n

=22.4×0.32

=7.2

I hope this helps

The steps involved in the manufacture of sulphuric acid by contact process:

(1) Sulphur (or iron pyrites) are burnt in air to form sulphur dioxide.

  S+O2→SO24FeS2+11O2→2Fe2O3+8SO2

(2) Catalytic oxidation of sulphur dioxide to sulphur trioxide.

  2SO2+O2V2O52SO3ΔrHo=−196.6kJ

The reaction is reversible and exothermic.

(3) Sulphur trioxide is dissolved in 98% sulphuric acid to form oleum (fuming sulphuric acid). 

  SO3+H2SO4→H2S2O7

(4) Oleum is diluted with water to form sulphuric acid of desired concentration.

    H2S2O7+H2O→2H2SO4

            and

Manufacture of H2SO4 by contact process involves three steps:

1. Burning of sulphur in air to generate SO2.

2. Conversion of SO2 to SO3 by oxidation with air in the presence of 

Answer:

"Endothermic reaction: In an endothermic reaction, the products are higher in energy than the reactants. Therefore, the change in enthalpy is positive, and heat is absorbed from the surroundings of the reaction."

Explanation:

When enthalpy is positive and delta H is greater than zero, this means that a system absorbed heat. This is called an endothermic reaction. When enthalpy is negative and delta H is less than zero, this means that a system released heat. This is called an exothermic reaction.

The sign of q for an endothermic process is positive because the system is gaining heat. A chemical reaction or physical change is exothermic if heat is released by the system into the surroundings. Because the surroundings are gaining heat from the system, the temperature of the surroundings increases.

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Answer:

for volume only liters can be used

Explanation:

A

Carbon monoxide gas can be prepared in lab by heating formic acid or oxalic acid with conc. H2SO4.

Procedure: Small amount of oxalic acid crystal is taken in a round- bottomed flask and all the apparatus are fitted as shown in figure. When conc. H2SO4 is poured in the flask through thistle funnel and heated then a mixture of CO and CO2 gas is formed. The mixture of gas is passed through a bottle containing NaOH solution where the CO2 gas is absorbed by NaOH.

2NaOH + CO2 → Na2CO3 + H2O

The pure CO gas is then collected in a gas jar by downward displacement of water.

▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓

[tex]\pmb{\red{\boxed{\sf{Na_{2}O(s)+H_{2}O(l)\dashrightarrow 2NaOH(aq)   }}}}[/tex]

▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓

Answer:

Explanation:

A measurement is the action of measuring something, or some amount of stuff. So it is important to measure certain things right, distance, time, and accuracy are all great things to measure. By measuring these things or in other words, by taking these measurements we can better understand the world around us.

Answer:

Measurement is the process of comparison of an unknown physical quantity with a known physical quantity.

It is important because measurement is needed in every day life we need measurement in simply cooking food to designing a house and many more other works.

Explanation:

hope this helps you.

Answer:

These are compounds.

Explanation:

As it is formed by chemically bonding of two elements C ( carbon) and H (hydrogen) .

Answer:

Butane and benzene are both compounds. They contain multiple elements bonded together in a specific ratio. Kerosene and gasoline are mixtures because they are combinations of several compounds. Oxygen is an element because it is made up of only one type of atom.

Explanation:

The volume of the liquid from the graduated cylinder is 22.5 mL

The last option (22.5 mL) is the correct option

The question seems to be incomplete

The image that completes the question is shown in the attachment below.

From the image, we observe that the liquid meniscus is between the 20 mL and 25 mL marks. That means the volume will lie in this range.

NOTE: The meniscus of a liquid is the upward or downward curve seen at the top of a liquid in a container.

The type of curve shown in the image is a concave meniscus and the volume of the liquid is read from the bottom of the curve.

To read the value from the graduated cylinder, we will first determine the difference between two consecutive lines. Between the 20 mL and 25 mL mark (two thick lines), we have 5 spaces separated by thin lines.

The measure between two consecutive lines is the difference between two thick lines divided by number of spaces between them

∴ The measure between two consecutive lines = (25mL - 20mL) ÷ 5

The measure between two consecutive lines = 5mL ÷ 5 = 1 mL

Now, to read the position of the liquid,

Starting from the 20 mL mark, the liquid exceeds two more lines + half way to the next line ( that is 2mL + 0.5 mL)

∴ The position of the liquid is 20 mL + 2mL + 0.5 mL = 22.5 mL

Hence, the volume of the liquid from the graduated cylinder is 22.5 mL

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Answer:

The answer is  22.5 mL

Explanation:

I hope this helps you :)

Answer:

16 g

Explanation:

Step 1: Write the balanced equation

2 Na + Cl₂ ⇒ 2 NaCl

Step 2: Identify the limiting reactant

The theoretical mass ratio (TMR) of Na to Cl₂ is 46:71 = 0.65:1.

The experimental mass ratio (EMR) of Na to Cl₂ is 10:10 = 1:1.

Since EMR > TMR, Cl₂ is the limiting reactant

Step 3: Calculate the mass of NaCl produced

The theoretical mass ratio of Cl₂ to NaCl is 71:117.

10 g Cl₂ × 117 g NaCl/71 g Cl₂ = 16 g NaCl

The correct option for the process used to refine aluminum from its bauxite ore is option D.

D. Smelting

The reason why smelting is the correct choice is as follows;

Bauxite is the aluminum ore from which alumina, also known as aluminum

oxide, Al₂O₃, is produced. Bauxite is extracted from the topsoil regions of

some subtropical and tropical regions, and the Bayer process is primarily

then used to produce alumina from the bauxite.

Aluminum is produced from the alumina by an aluminum smelting process

known as the Hall—Heroult electrolytic process which involves the use of a

carbon anode and direct current to produce aluminum by reducing the

aluminum oxide

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Answer:

Because elements of group  1 does not have stable electronic configuration and elements of group 18 have stable electronic configuration.

Explanation:

Because elements of group 1 do not contain stable electronic configuration and elements of group 18 include stable electronic configuration.

Group 1 elements contain the alkali metals, Li, Na, K, Rb, Cs, and Fr. The alkali metals exist all soft, shiny, and metallic when cut. They react efficiently with water, have low melting points and densities, and are good conductors of electricity. They all include one valence electron that they lose easily to form ions. Noble gas exists as any of the seven chemical elements that create up Group 18 (VIIIa) of the periodic table. The elements exist as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og).

The element of group 1 exist as reactive but those of group 18 exist as inert Because elements of group 1 do not contain stable electronic configuration and elements of group 18 include stable electronic configuration.

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Answer:

Explanation:

pretty sure its mixure.

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