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AS Chemistry P2 Prep.
H goes from minus 1 to 0??? That's a huge mistake. :P -
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Chemistry: Post your doubts here!
Is reflux necessary? Well could not remember it clearly. :P As long as the materials are mixed and conditions applied, the reaction occurs, yet taking equal amounts can ensure no remaining reactants afterwards I would say. ;) -
Chemistry: Post your doubts here!
(1) Advantages are -no pollution -high efficiency Disadvantages are -high cost & maintenance cost -difficulty of storage (since hydrogen and oxygen need to be liquid for massive storage) (2) Material: acid & alcohol Condition: concentrated sulphuric acid & heat (3)Eutrophication... -
Chemistry: Post your doubts here!
Reacted with Cr2O7(2-) under reflux, the destination shall be carboxylic acid. Any hydroxyl (-OH) and aldehyde (-CHO) groups will be converted into carboxylic acid groups (-CO2H). So the final product should be ethan-di-oic acid, HO2CCO2H or (CO2H)2. Skeletal formula represent carbon atoms with... -
AS Chemistry P2 Prep.
Anode: oxidation, since chloride ion reacted to form chlorine gas, oxidation number rises from -1 to 0. Cathode: reduction, since hydrogen ion reacted to form hydrogen gas, oxidation number drops from +1 to 0. And just a small hint: oxidation always happens at the anode and reduction at the cathode. -
Further Mathematics: Post your doubts here!
Sure, I took Pure Maths 1, 2 & 3 all in one year, along with Mechanics 1 & Statistics 1. -
Physics: Post your doubts here!
I think they describe decay from different points of view. A decay is spontaneous since the substance can initiate decay by itself. It need not any special conditions. A decay is random since the decay process is not programmed. The decay does not have any order i.e. which nucleus decays first... -
Mathematics: Post your doubts here!
Continuity correction is used when we approximate a discrete variable using a continuous variable. Like using X~N to approximate X~B, or X~N approximate X~Po -
AS Chemistry P2 Prep.
"heat under reflux" should be more reliable. Small-molecule halogenoalkanes are usually in gaseous phase under room temperature. Reflux can ensure that the haloalkane is kept inside the container during the entire reaction. -
AS Chemistry P2 Prep.
Paired electrons repel, so they have higher energy and are thus more easily removed. Phosphorus has its 3p orbital just half-filled, which is relatively stable. Sulphur has one paired electrons in 3p. The paired electrons shall have slightly higher energy, so it requires less energy to remove... -
AS Chemistry P2 Prep.
Yeah, Lithium is polarising enough to form lithium oxide after decomposition. 4LiNO3 = 2Li2O + 4NO2 + O2 -
AS Chemistry P2 Prep.
Oops... It also says "room temperature". Heat is not necessary. -
AS Chemistry P2 Prep.
Unless I am mistaken, SOCl2 and PCl5 don't need heating. They can perform substitution in under conditions. -
Chemistry: Post your doubts here!
HCl + NaOH = NaCl + H2O 1 mole of hydrochloric acid requires (at least) 1 mole of sodium hydroxide for complete reaction. So a certain amount of hydrochloric acid needs the same amount of sodium hydroxide to react completely. -
Mathematics: Post your doubts here!
[number without pink next to green] = [total number] - [number with pink next to green] total number, as calculated in (iii), is 9P3 = 504 number with pink next to green can be done this way: - find the number of choices that has both the pink and green cards, which is just, with the pink and... -
Mathematics: Post your doubts here!
Between 5000 and 6000, so the first digit must be 5. Then, allowed repetition of number, the following three digits each can have any one number from 1 to 6. That is, they each have 6 options. The total number is then 6 × 6 × 6 = 216 -
Chemistry: Post your doubts here!
High pressure and low temperature shall lead to relatively strong intermolecular forces. This means there is potential energy among the molecules. Ideal gases don't have any molecular potential energy. ;) -
Chemistry: Post your doubts here!
All electrons have negative charges so there are repulsive forces among them. In a covlent compound, the repulsion is obvious among bonding pairs and lone pairs. For a simple molecule, the covalent bonds stretch out from the centre in a 3D space. The relative strength of the repulsive forces... -
Further Mathematics: Post your doubts here!
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