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3 years ago

What were the first galaxies made of

1 answer:

5 0

The are made from star stuffs...
Galaxies are composed of stars, dust, and dark matter, all held together by gravity. Below we discuss galaxy formation, galactic collisions and other facts about these so-called “island universes.” The Milky Way Galaxy is organized into spiral arms of giant stars that illuminate interstellar gas and dust.
Hope that helps........ (◕‿◕✿)

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If you start with 30 moles of O2, how many moles of SiO2 can you make?

Ivanshal [37]

Answer:

30moles of SiO₂

Explanation:

Given parameters:

Number of moles of O₂ = 30moles

Unknown:

Number of moles of SiO₂ = ?

Solution:

To solve this problem, we need to write the reaction expression:

Si + O₂ → SiO₂

The reaction is balanced;

1 mole of O₂ will produce 1 mole of SiO₂

30mole of O₂ will produce 30moles of SiO₂

7 0

3 years ago

Part 1: Name the type of chemical reaction that occurs when calcium hydroxide (Ca(OH)2) reacts with nitric acid (HNO3).

liberstina [14]

Answer:

For 1: Neutralization reaction

For 2: Zinc is more reactive than lead and less reactive than calcium.

Explanation:

For (1):

When a base reacts with an acid to form a salt and water molecule, it is known as a neutralization reaction. The general equation follows:

$HX+BOH\rightarrow BX+H_2O$

The chemical equation for the reaction of calcium hydroxide and nitric acid follows:

$Ca(OH)_2(aq)+2HNO_3(aq)\rightarrow Ca(NO_3)_2(aq)+2H_2O(l)$

For (2):

A single displacement reaction is defined as the reaction in which a more reactive metal displaces a less reactive metal from its salt solution. The general chemical equation follows:

$A+BX\rightarrow AX+B$

where,

Metal A is more reactive than metal B

The reactivity of metals is judged by the reactivity series where a metal lying above in the series is more reactive than the metal lying below it.

From the reactivity series below,

Zinc lies above in the series than lead thus is more reactive and will easily replace lead from its aqueous solution.

While zinc lies below in the series than calcium thus is less reactive and will not easily replace calcium from its aqueous solution.

$Zn(s)+Pb(NO_3)_2(aq)\rightarrow Zn(NO_3)_2(aq)+Pb(s)$

$Zn(s)+CaCl_2(aq)\rightarrow \text{No reaction}$

5 0

3 years ago

Why is density referred to as a characteristic property of matter?

amm1812

Answer : Density of any particular matter remains the same at any concentration at any weight.

Density does not varies with the concentration. The formula for density is mass / volume.

So if the mass changes the density will change accordingly, also if the volume changes the density will get changed.

because, of the above reasons density is referred as a characteristic property of matter.

6 0

3 years ago

Predict the products of the following nuclear reactions...

koban [17]

1. According to Rutherford and soddy's law of Beta emission:

${K}^{42} \: ---> {Ca}^{40} + {2e}^{0}$

3. According to Rutherford and soddy's law of Alpha emission:

${U}^{238} \: ---> {Th}^{234} + {He}^{4}$

4. The process in which two or more light nuclei are combined to form a single nucleus with the release of tremendous amount of energy is called a nuclear fusion. The inner core of Sun is at very high temperature and is suitable for fusion. In fact the source of energy of Sun and other stars is nuclear fusion reactions.

6 0

3 years ago

Find the potentials of the following electrochemical cell:

melomori [17]

Answer: 0.18 V

Explanation:-

$Cd/Cd^{2+}(0.10M)//Ni^{2+}(0.50M)?Ni$