A: because the light is lower than the hole, it will come in at in inclined angle. if the hole was say at the same level as the hole, it would shine straight to the other side of the box
Answer:
30 hot dogs
Explanation:
It is given that :
There are 4 packets of eight wieners, i.e. 4 x 8 = 32 wieners
There are 3 bags of ten buns, i.e. 3 x 10 = 30 buns
One hot dogs need 1 bun and 1 wiener to make a hot dog.
There are 30 buns, so 30 hot dogs can be made out by using all the 30 buns and the 30 wieners out of the 32 wieners.
Therefore, 30 hot dogs.
And the number of extra wieners left = 32 - 30 = 2 wieners.
All atoms consist of a nucleus with protons and neutrons that is surrounded by a sea of electrons. If Uranium-235 is bombarded with a neutron then the atom's atomic number will remain the same but its mass will increase by 1 unit. Thus, it will temporarily become Uranium-236.
Answer:
- <u><em>It is positive when the bonds of the product store more energy than those of the reactants.</em></u>
Explanation:
The <em>standard enthalpy of formation</em>, <em>ΔHf</em>, is defined as the energy required to form 1 mole of a substance from its contituent elements under standard conditions of pressure and temperature.
Then, per defintion, when the elements are already at their standard states, there is not energy involved to form them from that very state; this is, the standard enthalpy of formation of the elements in their standard states is zero.
It is not zero for the compounds in its standard state, because energy should be released or absorbed to form the compounds from their consituent elements. Thus, the first choice is false.
When the bonds of the products store more energy than the those of the reactants, the difference is:
- ΔHf = ΔHf products - ΔHf reactants > 0, meaning that ΔHf is positive. Hence, the second statement is true.
Third is false because forming the compounds may require to use (absorb) or release (produce) energy, which means that ΔHf could be positive or negative.
Fourth statement is false, because the standard state of many elements is not liquid. For example, it is required to supply energy to iron to make it liquid. Thus, the enthalpy of formation of iron in liquid state is not zero.
