M = 4 g = 4/1000 kg = 0.004 kg, θ₂ = 21.0°C, θ₁ = 0°C , c = 0.44kJ/kg°C,
Q = mc(θ₂ - θ₁)
Q = 0.004*0.440*(21 - 0)
Q = 0.03696 kJ
0.03696 kJ<span> of heat is absorbed.</span>
Answer:
(i) Oxidizing Agent: NO2 / Reducing Agent NH3-
(ii) Oxidizing Agent AgNO3 / Reducing Agent Zn
Explanation:
(i) 8NH3( g) + 6NO2( g) => 7N2( g) + 12H2O( l)
In this reaction, both two reactants contain nitrogen with a different oxidation number and produce only one product which contains nitrogen with a unique oxidation state. So, nitrogen is oxidized and reduced in the same reaction.
Nitrogen Undergoes a change in oxidation state from 4+ in NO2 to 0 in N2. It is reduced because it gains electrons (decrease its oxidation state). NO2 is the oxidizing agent (electron acceptor).
Nitrogen Changes from an oxidation state of 3- in NH3 to 0 in N2. It is oxidized because it loses electrons (increase its oxidation state). NH3 is the reducing agent (electron donor)
(ii) Zn(s) +AgNO3(aq) => Zn(NO3)2(aq) + Ag(s)
Ag changes oxidation state from 1+ to 0 in Ag(s).
Ag is reduced because it gains electrons and for this reason and AgNO3 is the oxidizing agent (electron acceptor)
Zn Changes from an oxidation state of 0 in Zn(s) to 2+ in Zn(NO3)2. It is oxidized and for this reason Zn is the reducing agent (electron donor).
Balanced equation:
Zn(s) +2AgNO3(aq) => Zn(NO3)2(aq) + 2Ag(s)
Instrumental methods of analysis rely on machines.The visualization of single molecules, single biological cells, biological tissues and nanomaterials is very important and attractive approach in analytical science.
There are several different types of instrumental analysis. Some are suitable for detecting and identifying elements, while others are better suited to compounds. In general, instrumental methods of analysis are:
-Fast
-Accurate (they reliably identify elements and compounds)
-Sensitive (they can detect very small amounts of a substance in a small amount of sample)
The thing that two changes have in common that snails growing shells and rust forming on a bicycle frame is option D. Both are caused by cooling.
<h3>How come snails develop shells?</h3>
Calcium carbonate is said to be the material that makes up the shell. The snail's shell expands as it grows to accommodate its growing body. Snails and slugs are also members of the mollusc family of creatures.
Therefore, note that air that has been mixed with the metal can make rust to develop. and as such, option D. Both are caused by cooling. is correct.
Learn more about snails growing shells from
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See full question below
What do these two changes have in common? snails growing shells rust forming on a bicycle frame Select all that apply.
A. Both are only physical changes.
B. Both are caused by heating.
C. Both are chemical changes.
D. Both are caused by cooling
In 1869 he published a table of the elements organized by increasing atomic mass.
Mendeleev is called the "father of the modern periodic table
stated that if the atomic weight of an element caused it to be placed in the wrong group, then the weight must be wrong. (He corrected the atomic masses of Be, In, and U)
was so confident in his table that he used it to predict the physical properties of three elements that were yet unknown.
After the discovery of these unknown elements between 1874 and 1885, and the fact that Mendeleev's predictions for Sc, Ga, and Ge were amazingly close to the actual values, his table was generally accepted.
However, in spite of Mendeleev's great achievement, problems arose when new elements were discovered and more accurate atomic weights determined.
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