Answer:
A. unexpected change in odor
Explanation: Common physical changes include melting, change of size, volume, color, density, and crystal form. Example the classic baking soda and vinegar reaction provides evidence of a chemical change due to the formation of a gas and a temperature change.
Reaction of option c produces precipitate.
Rhodium on reacting with potassium phosphate produces rhodium phosphate which remain in solution due to low lattice energy for rhodium phosphate.
Niobium on reacting with lithium carbonate produces niobium carbonate and it will remain in aqueous form.
Cobalt on reacting with zinc nitrate produces cobalt nitrate. This, Co(NO3 )2 is insoluble precipitate and settles at bottom whereas zinc ion will remain in solution as follows:
Potassium ion on reacting with sodium sulfide produces potassium sulfide which remain in solution
Answer:
1. Exothermic.
2. Yes, released.
3. 38.65KJ of heat is released.
Explanation:
The equation for the reaction is given below:
2NO2 —> N2O4...... ΔH = –55.3KJ
1. The sign of the enthalpy change, ΔH tells whether the reaction is endothermic or exothermic. Since the sign of the enthalpy change, ΔH is negative, the reaction is exothermic.
2. The negative sign indicate that heat is released to the surrounding. Since the reaction is generally an exothermic reaction, 64.3g of NO2 will also release heat to the surroundings.
3. Molar mass of NO2 = 14 + (16x2) = 46g/mol
Mass of NO2 from the balanced equation = 2 x 46 = 92g.
From the balanced equation above:
92g of NO2 reacted to release –55.3KJ of heat.
Therefore, 64.3g of NO2 will react to release = (64.3 x –55.3)/92 = 38.65KJ of heat.
Therefore, 38.65KJ of heat is released.
Answer: For most of the life the chromosomes exists in a loose noodle like structure. They become compact to fit into a very small space.
Explanation: The chromosomes consists of a very long DNA that is linear. The liner DNA also has many proteins associated with it which is called as histone proteins.
These proteins fold and gets packed into a compact form from loose noodle or thread like structure.
This is necessary to get into a compact structure because being in linear form would require much space which is not possible. So as to manage the space and many processes like replication, repair and gene expression it is necessary for the chromosomes to get compact.
A. Strong acids have a high ionization.