Please help me it has to be right

1. In any nuclear reaction, nuclei are transformed in some way.

Grace [21]

<span>1. In any nuclear reaction, nuclei are transformed in some way.

True

2. Two fissionable substances commonly used in nuclear reactors and nuclear weapons include uranium-235 and plutonium-239.

True

3. Fission reactions can be controlled; thus, they are used to create energy and electricity. But fusion reactions are uncontrollable and require too much energy for economical use.

True

4. Fission reactions occur at such high temperatures in the Sun that the Sun appears to glow.

False

Hope this answers the question. Have a nice day.</span>

4 0

3 years ago

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If 42.7 of 0.208 M hydrochloric acid are needed to completely neutralize a solution of calcium hydroxide, how many grams of calc

Montano1993 [528]

Answer:

0.329 g

Explanation:

In the context of this problem, we have a chemical reaction between hydrochloric acid and calcium hydroxide. HCl is the acid here and calcium hydroxide is the base. Hence, we have an acid-base reaction, also known as neutralization reaction.

In a neutralization reaction, water is produced as a product, as well as a salt that we obtain after we exchange the cations: calcium bonds to chloride and hydrogen bonds to hydroxide (the latter is the formation of water). This means we also produce calcium chloride as a product. The overall reaction represents this as:

$Ca(OH)_2(aq)+2 HCl (aq)\rightarrow CaCl_2 (aq)+2 H_2O (l)$

Firslt of all, we wish to find the number of moles of HCl present. Having molarity and volume, this is done by applying the molarity formula. It states that molarity is equal to the rate between moles and volume:

$c_{HCl}=\frac{n_{HCl}}{V_{HCl}}$

Rearranging for moles of HCl, n:

$n_{HCl}=c_{HCl}V_{HCl}$

Based on stoichiometry of the balanced chemical equation, notice that 1 mole of calcium hydroxide reacts with 2 moles of HCl, meaning:

$n_{Ca(OH)_2}=\frac{1}{2} n_{HCl}=\frac{1}{2}c_{HCl}V_{HCl}$

Now that we have the expression for moles, we may also express moles of calcium hydroxide as the ratio between its mass and molar mass:

$n_{Ca(OH)_2}=\frac{m_{Ca(OH)_2}}{M_{Ca(OH)_2}}$

Using the last two equations, we see that:

$\frac{1}{2}c_{HCl}V_{HCl}=\frac{m_{Ca(OH)_2}}{M_{Ca(OH)_2}}\\\therefore m_{Ca(OH)_2}=\frac{1}{2}c_{HCl}V_{HCl}M_{Ca(OH)_2}$

Substitute the given data, as well as the molar mass of calcium hydroxide:

$m_{Ca(OH)_2}=\frac{1}{2}\cdot0.208 M\cdot0.0427 L\cdot74.093 g/mol=0.329 g$

8 0

4 years ago

Which of these solid compounds are most likely to have its dominant bonding mechanism as covalent? (Select all that are true.)

I am Lyosha [343]

The compounds that have covalent bonding as their dominant bonding scheme are diamond and silica.

A covalent bond is formed between two nonmetals. Usually, when two nonmetals combine, electrons are shared between the two atoms involved in the bond.

Now, the solids diamond and silica are predominantly covalent solids. The atoms that combine in diamond are carbon atoms(nonmetals) while the atoms that combine in silica are silicon and oxygen (nonmetals also)

Hence, diamond and silica both have covalent bonding as their dominant bonding scheme.

Learn more: brainly.com/question/11527546

8 0

3 years ago

Which of the following statements is TRUE for the following situation:

Mekhanik [1.2K]

Answer:

The electron in xenon are dropping more energy levels than helium

4 0

3 years ago

How many atoms are in a 158.69 g sample of nickel?

Alchen [17]

<h3>Answer:</h3>

1.6283 × 10²⁴ atoms Ni

<h3>General Formulas and Concepts:</h3>

<u>Math</u>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right<u> </u>

<u>Chemistry</u>

<u>Atomic Structure</u>

Reading a Periodic Table
Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

<u>Stoichiometry</u>

Use Dimensional Analysis

<h3>Explanation:</h3>

<u>Step 1: Define</u>

158.69 g Ni

<u>Step 2: Identify Conversions</u>

Avogadro's Number

Molar Mass of Ni - 58.69 g/mol

<u>Step 3: Convert</u>

Set up: $\displaystyle 158.69 \ g \ Ni(\frac{1 \ mol \ Ni}{58.69 \ g \ Ni})(\frac{6.022 \cdot 10^{23} \ atoms \ Ni}{1 \ mol \ Ni})$
Multiply/Divide: $\displaystyle 1.62827 \cdot 10^{24} \ atoms \ Ni$

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 5 sig figs.</em>

1.62827 × 10²⁴ atoms Ni ≈ 1.6283 × 10²⁴ atoms Ni

8 0

3 years ago