_______ store food or pigments ( I'm learning about cells)

PLEASE HELP ME PLEASEEEE if you could just answer one of these questions that would be amazing!

Nadusha1986 [10]

The answer to this question is B

4 0

3 years ago

In which of the following substances does sharing of electrons between two atoms occur?

malfutka [58]

Answer:- B- $SO_4^-^2$

Explanations:- Sharing of electrons takes place between non metals and the bond formed by the sharing of electrons is known as covalent bond. In first choice we only have a zinc metal and so no sharing of electrons would be possible here.

In third choice we have NaCl. Na is a metal and Cl is a non metal. The property of metals is to transfer its valence electrons to the non metal and the bond formed is known as ionic bond. So, third choice is also not correct.

In choice B we have sulfate ion that has sulfur and oxygen atoms and both of these are non metals. So, sharing of electrons is present here between the S and O atoms and covalent bonds are formed.

So, choice B- $SO_4^-^2$ is the right answer.

6 0

3 years ago

In a polar covalent bond,

almond37 [142]

the answer is C because convalent bond is being bonded to an anion

3 0

3 years ago

Read 2 more answers

A student adds 0.40g of sodium hydroxide to a clean, dry 250 mL beaker and leaves the beaker and leaves the beaker on the lab ta

kherson [118]

2 NaOH (s) + CO₂ (g) → Na₂CO₃ (s) + H₂O (l)

Explanation:

The most probably chemical reaction is:

2 NaOH (s) + CO₂ (g) → Na₂CO₃ (s) + H₂O (l)

Sodium Hydroxide (solid) + Carbon Dioxide (gas) → Sodium Carbonate (solid) + Water (gas)

In this reaction the water you obtain have to be in liquid form because the reaction takes place at room temperature. However because the student left the beaker for 24 hours, the water have a plenty of time to evaporate, so in the end only sodium carbonate (Na₂CO₃) remained in the beaker.

number of moles = mass / molar weight

number of moles of NaOH = 0.4 / 40 = 0.01 moles

Taking in account the chemical reaction, we devise the following reasoning:

if 2 moles of NaOH produce 1 mole of Na₂CO₃

then 0.01 moles of NaOH produce X mole of Na₂CO₃

X = (0.01 × 1) / 2 = 0.005 moles of Na₂CO₃

mass = number of moles × molar weight

mass of Na₂CO₃ = 0.005 × 106 = 0.53 g

mass of Na₂CO₃ = mass of beaker and its contents after 24h - mass of empty beaker

mass of Na₂CO₃ = 113.09 - 112.58 = 0.51 g which is close the theoretical value of 0.53 g.

Learn more about:

number of moles

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5 0

3 years ago

Which oxide(s) of manganese have a mass percent of the metal that is greater than 50%?MnO MnO2 Mn2O3All of these102

Hunter-Best [27]

Answer:

All of these

Explanation:

In MnO:

mass of Mn = 55 g (as 1 mole of Mn weighs 55 g)

mass of O = 16 g (as 1 mole of O weighs 16 g)

The mass percent of metal Mn= $\frac{55}{55+16}\times100=\frac{55}{71}\times100=77.46$

In MnO2:

mass of Mn = 55 g

mass of O = 2*16 = 32 g

The mass percent of metal Mn= $\frac{55}{87}\times100=63.22$

In Mn2O3:

mass of Mn = 2*55 = 110 g

mass of O = 3*16 = 48 g

The mass percent of metal Mn= $\frac{110}{158}\times100=69.62$

In all the cases the mass percent of metal is greater than 50.

5 0

3 years ago