18 valance electrons, Hope this helps!
Answer:
it is because of Dark Matter
Dark Matter, component of the universe whose presence is discerned from its gravitational attraction rather than its luminosity. Dark matter makes up 30.1 percent of the matter-energy composition of the universe; the rest is dark energy (69.4 percent) and “ordinary” visible matter (0.5 percent).
Dark matter is composed of particles that do not absorb, reflect, or emit light, so they cannot be detected by observing electromagnetic radiation. Dark matter is material that cannot be seen directly.
Explanation:
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To balance any redox equation, first divide the reaction into two half reactions, and balance the atom whose oxidation number is changing:
<span>NO2 --> NH3 </span>
<span>H2 --> H2O </span>
<span>Next, balance oxygens by adding H2O where needed, and then balance hydrogen by adding H+: </span>
<span>NO2 --> NH3 + 2 H2O </span>
<span>H2O + H2 --> H2O </span>
<span>7 H+ + NO2 --> NH3 + 2 H2O </span>
<span>H2O + H2 --> H2O + 2 H+ </span>
<span>Next, balance charges by adding electrons (e-): </span>
<span>7 H+ + NO2 + 7 e- --> NH3 + 2 H2O </span>
<span>H2O + H2 --> H2O + 2 H+ + 2 e- </span>
<span>Now, multiply one or both equations by small numbers to make the number of electrons the same in the two half reactions. In this case, multiply the top equation by 2 and the bottom one by 7 to give you 14 electrons in each half reaction: </span>
<span>14 H+ + 2 NO2 + 14 e- --> 2 NH3 + 4 H2O </span>
<span>7 H2O + 7 H2 --> 7 H2O + 14 H+ + 14 e- </span>
<span>Finally, add the two half reactions and simplify by cancelling anything that is on both sides. This will give you the final balanced reaction: </span>
<span>2 NO2 + 7 H2 --> 2 NH3 + 4 H2O </span>
<span>So, the answer to the original question is (A) 7
</span>
<h2>
Answer:</h2>
- Cu(s) + 2AgNO3(aq) → Cu(NO3)2(aq) + 2Ag(s).
<u>Moles Cu present</u> = 100g Cu x 1 mol Cu/63.55g
= 1.574moles Cu
<u>Mass of Ag produced</u> = 1.574mol Cu x 2mol Ag / 1mol Cu x 107.9g Ag/mol Ag
= 340.g Ag
Answer:
Litmus paper is one type of acid-base indicator. The paper is imbued with dye derived from lichens that change color in response to the presence of an acid or base. ... Red paper is used to detect alkaline pH and will turn a shade of blue in the presence of a basic solution.
