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2 years ago

Which is not true about the upper paleolithic period?.

1 answer:

5 0

Answer:The Upper Paleolithic period started about 40,000 years BC and ended about 10,000 years BC. So it took place between 40,000 and 10,000 BC. After that started the Mesolithic Era ( 10,000 to 4,000 BC ). Stone tools in the Upper Paleolithic period were primarly blade-based technology. Also this period is well known for the cave art and paintings of animals. Answer: C ) The period took place between 40,000 and 4,000 BC ( not true ).

Explanation:

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A 367.8 g sample of potassium chlorate was decomposed according to the following equation:

Pie

The answer is A i did this before hope this helps

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3 years ago

Attempt 3 During an experiment, a student adds 2.90 g CaO 2.90 g CaO to 400.0 mL 400.0 mL of 1.500 M HCl 1.500 M HCl . The stude

kondor19780726 [428]

Answer:

Explanation:

Equation of the reaction:

CaO(s) + 2H+(aq) -----> Ca2+(aq) + H2O(g)

The ∆Hrxn would be for one mole of CaO reacted or 2 moles of H+, whichever is the limiting reactant.

Number of moles = mass ÷ molar mass

Molar mass of CaO = 40 + 16

= 56 g/mol

moles of CaO = 2.90/56

= 0.0518 mol

Number of moles = concentration × volume

moles of HCl = 400 × 10^-3 × 1.500 = 0.6 moles

Moles of HCl = moles of H+

From the equation, 1 mole of CaO reacted with 2 moles of H+ to give 1 mole of water.

To find the limiting reagent,

0.6 mole of H+/2 moles of H+ × 1 mole of CaO

= 0.3 moles of CaO(> 0.0518 moles)

So, CaO is limiting reactant.

∆H = m × Cp × ∆T

m = density × volume

= 400 × 1

= 400 g

Cp = 4.184 J/g-ºC

∆T = +6 ºC

∆H = 400 × 4.184 × 6

= 10041.6 J

Since the reaction is exothermic,

∆Hrxn = -∆H/mol(CaO)

= -10041.6/0.0518

= -193853 J

= -193.9 kJ/mol.

3 0

3 years ago

5.How many moles of uranium are in 50 grams of uranium?

Y_Kistochka [10]

50g U ( 1mol/ 238.03g) = .2 moles

238.03 is the molar mass of uranium- can be found on periodic table

4 0

3 years ago

Submit your data table and atom diagram drawings. Remember to proofread your work before sub

eimsori [14]

Answer:

wym

Explanation:

3 0

3 years ago

The combustion of liquid methanol has a change in enthalpy of -1278 kJ. How much energy will you get from burning 245.0 g of met

Nookie1986 [14]

Answer : 9773 kJ

Explanation:

Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and $\Delta H$ for the reaction comes out to be negative.

To calculate the moles :

$\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}$

$\text{Moles of methanol}=\frac{245.0g}{32.04/mol}=7.647moles$

Given : Change in enthalpy on combustion of 1 mole of methanol = -1278 kJ

According to stoichiometry :

1 mole of methanol produce energy = 1278 kJ

Thus 7.647 moles of methanol produce energy = $\frac{1278}{1}\times 7.647=9773kJ$

Thus 9773 kJ of energy is produced from burning 245.0 g of methanol in excess oxygen

3 0

3 years ago