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3 years ago

Why burning of wood and cutting it into small pieces are considered as two different types

Chemistry

2 answers:

Mila [183]3 years ago

8 0

Answer:

burning causes pollution cutting results furniture

Explanation:

are u a nepali ?

gogolik [260]3 years ago

6 0

Answer:

burning of wood, new substances are formed and hence it is a chemical change. While cutting the wood into small pieces no new substance is formed, thus it is a physical change. Hence, burning of wood and cutting it into small pieces are considered as two different types of changes.

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Which correctly describes elements in the same group? select one:

Nadya [2.5K]

They have the same amounts of electrons

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3 years ago

Darwin's theorized that three conditions were necessary for natural selection to occur, which of the following is NOT one of the

Mekhanik [1.2K]

Answer:

The correct option is: stable environment

Explanation:

According to the Darwin's theory, natural selection is the concept by which all the small useful variations of traits are preserved.

According to Darwin, there are three <u>necessary and sufficient conditions</u> for the occurrence of natural selection:

1. struggle for existence

2. variation

3. inheritance

These conditions are said to be necessary because if these conditions are not satisfied then natural selection does not occur.

These conditions are said to be sufficient because if these conditions are satisfied, then natural selection will most definitely occur.

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3 years ago

Define atomic mass unit?

sveticcg [70]

Atomic mass unit is the standard unit that is used for indicating mass on an atomic or molecular scale

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3 years ago

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How do electrons differ from protons and neutrons? A. They do not move. B. They are larger. C. They are not in a fixed position.

nikdorinn [45]

Hi!

Electrons are particles which basically 'orbit' around the nucleus. Protons and neutrons are condensed, in a fixed position inside the nucleus.

With this in mind, the answer will be C.

Hopefully, this helps! =)

4 0

3 years ago

Read 2 more answers

Glycolic acid, which is a monoprotic acid and a constituent in sugar cane, has a pKa of 3.9. A 25.0 mL solution of glycolic acid

Phoenix [80]

Answer:

pH = 8.0

Explanation:

First, we have to calculate the moles of NaOH.

$35.8 \times 10^{-3}L.\frac{0.020mol}{L} =7.2\times 10^{-4}mol$

Let's consider the balanced equation.

C₂H₄O₃ + NaOH ⇒ C₂H₃O₃Na + H₂O

The molar ratio C₂H₄O₃: NaOH: C₂H₃O₃Na is 1: 1: 1. So, when 7.2 × 10⁻⁴ moles of NaOH react completely with 7.2 × 10⁻⁴ moles of C₂H₄O₃ they form 7.2 × 10⁻⁴ moles of C₂H₃O₃Na.

The concentration of C₂H₃O₃Na is:

$\frac{7.2\times 10^{-4}mol}{60.8 \times 10^{-3}L} =0.012M$

C₂H₃O₃Na dissociates according to the following equation:

C₂H₃O₃Na(aq) ⇒ C₂H₃O₃⁻(aq) + Na⁺(aq)

C₂H₃O₃⁻ comes from a weak acid so it undergoes basic hydrolisis.

C₂H₃O₃⁻ + H₂O ⇄ C₂H₄O₃ + OH⁻

If we know that pKa for C₂H₄O₃ is 3.9, we can calculate pKb for C₂H₃O₃⁻ using the following expression:

pKa + pKb = 14

pKb = 14 -3.9 = 10.1

10.1 = -log Kb

Kb = 7.9 × 10⁻¹¹

We can calculate [OH⁻] using the following expression:

[OH⁻] = √(Kb.Cb) <em>where Cb is the initial concentration of the base</em>

[OH⁻] = √(7.9 × 10⁻¹¹ × 0.012M) = 9.7 × 10⁻⁷ M

Now, we can calculate pOH and pH.

pOH = -log [OH⁻] = -log (9.7 × 10⁻⁷) = 6.0

pH + pOH = 14

pH = 14 - pOH = 14 - 6.0 = 8.0

7 0

3 years ago