Combining oxygen gas and hydrogen gas to form liquid water is a chemical change. Pretty sure the rest are physical changes because a chemical change happens when a substance is altered completely. A physical change is when a substance keeps its components (I dunno what word to use) but just changes into a diferent shape. At least thats how my teacher explained it to me.
Answer:
Option B is correct.
The net ionic chemical reaction when Cu(NO₃)₂ reacts with water is
Cu²⁺(aq) + H₂O(l) ⇌ Cu(OH)¹⁺(aq) + H¹⁺(aq)
Explanation:
When ions dissolve in polar solvents (in water especially), then often attract ions of opposite signs.
Cu(NO₃)₂ dissolves into Cu²⁺ & NO₃⁻ and water contains H¹⁺ & OH⁻
The Cu²⁺ attracts the OH⁻ from water, thereby giving the Cu(OH)¹⁺ ion (with a net charge of +2-1 = +1) and the NO₃⁻ takes up the H⁺ ion.
Answer 1: The electron is a subatomic particle that has a negative charge. Electron cannot be sub-divided further. An electron has a mass that ia ~ 1/1836 that of the proton.
The positron is also refereed as an antielectron. The positron has the charge of +1e, a spin of 1⁄2. The similarity between positron and electron is that they have same mass.
Answer 2: <span>Positron decay occurs in nuclei having heavy mass. Positron emission decreases proton number relative to the neutron number. Positron also exhibits nuclear transmutation thereby producing an atom of a different element, as compared to parent element,. Them atomic number of daughter element is less as compared to parent element by 1.
Example: </span><span><span>23 12</span>Mg </span><span>→ </span><span><span>23 11</span>Na </span><span> + </span><span>e+ </span><span>+ energy
</span><span>
Answer 3: </span><span>Electron capture is also referred as </span>K-electron capture. It <span>involves absorption of energy, thereby resulting in loss of electron usually from K or L shell. In this process,following thing occurs simultaneously
i) a nuclear proton present in nuclei changes to a neutron, after reacting with an electron which falls into the nucleus from one of its orbitals (preferentially from K or L)
2) Emission of an electron neutrino.
Following is an example of K-electron capture.
7 4Be + 0 -1e </span>→ 7 3Li + energy
Answer 4: Following are the distinct features of <span>transmutations caused by positron emissions and electron capture.
i) Positron: </span><span>A proton get converted into neutron due to radio-active process. This process results in the emission of positron and neutrino. The<span> process results in decrease in atomic number by one unit, and however atomic mass number remains unchanged.
ii) Electron capture: </span></span><span>A electron from the low energy level (K-shell or L-shell) falls into the nucleus. Due to this proton is converted into neutron. During this process, neutrino is emitted from the nucleus. As seen in positron emission, t<span>he atomic number goes down by one unit, but atomic mass number remains unchanged.</span></span>
Answer:
The mass % of HNO3 in the solution is 71.0 %
Explanation:
Step 1: Data given
Density of HNO3 = 1.42 g/mL
Concentration = 16 M = 16 mol /L
Molar mass HNO3 = 63.01 g/mol
Assume the volume = 1L or 1000 mL
Step 2: Calculate mass of the solution
Mass = density * volume
Mass = 1.42 g/mL * 1000 mL
Mass = 1420 grams
Step 3: Calculate moles HNO3
Moles = molarity * volume
Moles = 16 M * 1L
Moles = 16 moles
Step 4: Calculate mass HNO3
Mass HNO3 = moles * molar mass
Mass HNO3 = 16.0 moles * 63.01 g/mol
Mass HNO3 = 1008.16 grams
Step 5: Calculate the mass percent
mass % = (1008.16 grams / 1420 grams) *100%
mass % = 71.0 %
The mass % of HNO3 in the solution is 71.0 %
ANSWER: From this experiment, Jeff can conclude that the heat capacity of oil is lower than that of water which means that oil requires less energy per gram of liquid in order to change its temperature.
