Erbium (Er) is element 68 on the periodic table. A sample contains 5.04*1023 atoms of Er. Calculate the amount of Er.

What kind of bond is the result of the transfer of an electron? A. An ionic bond B. A metallic bond C. A covalent bond D. A hydrogen bond

Water flowing at the rate of 13.85 kg/s is to be heated from 54.5 to 87.8°C in a heat exchanger by 54 to 430 kg/h of hot gas flowing counterflow and entering at 427°C (cpm = 1.005 kJ/kg · K). The overall Uo = 69.1 W/m^2. K.

Is vapeing bad for you and explain y

Why has the atomic theory changed so much over the last several centuries?

what the new pressure in kpa of an empty 200 ml aerosol at room temperature 22C and 45 kps if it is thrown into an 800C fire and balloons in size to 1.50L?

Which statement about neutrons is true? A. Neutrons travel around the nucleus of an atom. B. The number of neutrons in an atom always equals the number of electrons. C. Neutrons have less mass than electrons. or D. A neutron has no charge.

Of these gases, which has the fastest-moving molecules (on average) at a given temperature?

What is the oxidation number for zinc? How does zinc's electron configuration account for this oxidation number?

Which of the following experimental observations proved that the idea of matter and mass being evenly distributed in an atom was flawed? A. Less than 1% of the alpha particles went un-deflected through the gold foil. B.

Calculate the energy E of a sample of 3.50 mol of ideal oxygen gas (O2) molecules at a temperature of 310 K. Assume that the molecules are free to rotate and move in three dimensions, but ignore vibrations.