All categories

3 years ago

Which of the following is true?

Chemistry

2 answers:

kotykmax [81]3 years ago

6 0

Anwser is C for cesium

Inessa05 [86]3 years ago

6 0

Answer:

D. Lithium is the least reactive element in group 1, because it is the smallest and holds its valence electron more tightly than the others in the same group.

Explanation:

Lithium is at the top of group one and has only two energy levels. It has the smallest atomic radius of all the elements in group one. This means it's valence electron is the closest one to the nucleus of all the group 1 elements. The nucleus holds this electron more tightly than other group 1 nuclei which is why lithium is the least reactive of all the group 1 metals.

You might be interested in

2500m into kilometer

Alex777 [14]

<h2>Answer</h2>

1 meter = 1000 km

2500 meter = 2500/1000 km

= 2.5 km

8 0

3 years ago

Find the theoretical oxygen demand for the

never [62]

Answer:

a) 213.3 mg/L

b) 62.61 mg/L

c) 0.0225 mg/L

Explanation:

Theoretical oxygen demand (ThOD)is essentially the amount of oxygen required for the complete degradation of a given compound into the final oxidized products

a) Given:

Concentration of acetic acid, $[CH3COOH]$ = 200 mg/L

$CH3COOH + 2O2 \rightarrow 2CO2 + 2H2O$

$ThOD = \frac{mass\ O2}{mass\ CH3COOH} * conc. CH3COOH$

Based on the reaction stoichiometry:

mass of $CH3COOH$ = 60 g

mass of $O2$ = 2(32) = 64 g

$ThOD = \frac{64 g}{60 g} * 200mg/L = 213.3 mg/L$

b) Given:

Concentration of ethanol, $[C2H5OH]$ = 30 mg/L

$C2H5OH + 3O2 \rightarrow 2CO2 + 3H2O$

$ThOD = \frac{mass\ O2}{mass\ C2H5OH} * conc. C2H5OH$

Based on the reaction stoichiometry:

mass of $C2H5OH$ = 46 g

mass of $O2$ = 3(32) = 96 g

$ThOD = \frac{96 g}{46 g} * 30mg/L = 62.61 mg/L$

c) Given:

Concentration of sucrose, $[C12H22O11]$ = 50 mg/L

$C12H22O11 + 12O2 \rightarrow 12CO2 + 11H2O$

$ThOD = \frac{mass\ O2}{mass\ C22H22O11} * conc. C12H22O11$

Based on the reaction stoichiometry:

mass of $C12H22O11$ = 342 g

mass of $O2$ = 12(32) = 384 g

$ThOD = \frac{384 g}{342 g} * 50mg/L = 0.0225 mg/L$

7 0

3 years ago

What was one idea Dalton taught about atoms?

gizmo_the_mogwai [7]

Explanation:

All atoms of one type were identical in mass and properties.

3 0

3 years ago

Strontium carbonate + sulphuric acid, chemical equation

tangare [24]

<h3>Answer:</h3>

SrCO₃ + H₂SO₄ → SrSO₄ + H₂O + CO₂

<h3>Explanation:</h3>

We are required to complete the chemical equation given;

strontium carbonate + sulfuric acid → ??

We know that, carbonates reacts with acids to form a salt, water and carbon dioxide.
Strontium carbonate reacts with sulfuric acid to form strontium sulfate, water and carbon dioxide.
Therefore, the equation for the reaction is;

SrCO₃ + H₂SO₄ → SrSO₄ + H₂O + CO₂

The equation is balanced as the number of atoms of each element are equal on both sides of the equation.

7 0

3 years ago

Answer the following questions…

Zina [86]

The concentration of the hydronium ion in hydrochloric acid is 0.0045 M, and the pH of the solution is 2.34.

pH is the potential of the hydrogen or the hydronium ions in the aqueous solution.

As the solution contains $4.5 \times 10^{-3} \;\rm M\;$ HCl the concentration of the hydronium ion will be the same, $4.5 \times 10^{-3} \;\rm M.$

The pH of the solution is calculated as:

$\begin{aligned} \rm pH &= \rm -log[H^{+}]\\\\&= - \rm log (4.5 \times 10^{-3})\\\\&= 2.34\end{aligned}$

The concentration of the hydroxide ion is calculated from pH and hydronium ion as:

$\begin{aligned} \rm [H_{3}O^{+}][OH^{-}] &= 10^{-14}\\\\&= \dfrac{1 \times 10^{-14}}{4.5 \times 10^{-3}}\\\\&= 2.2 \times 10^{12}\end{aligned}$

Now, for the calcium hydroxide solution, the calculations are shown as,

$\begin{aligned} \rm (H_3}\rm O^{+}) &= \rm antilog (-pH)\\\\&= \rm antilog (-8)\\\\&= 10^{-8} \;\rm M\end{aligned}$

pOH is calculated as:

$\begin{aligned} \rm pOH &= 14- 8 = 6\\\\\rm [OH^{-}] &= \rm antilog (-6)\\\\&= 10^{-6} \end{aligned}$

The concentration of calcium hydroxide is calculated as:

$\begin{aligned} &= \dfrac{1}{2} \times \rm [OH^{-}]\\\\&= 5 \times 10^{-4} \;\rm M\end{aligned}$

Therefore, the pH and the pOH give the concentration of the hydrogen or the hydronium ion and the hydroxide ion.

Learn more about pH and pOH here:

brainly.com/question/16062632

#SPJ1

3 0

2 years ago