Which is the best procedure to make a permanent magnet? a) placing a magnetically hard material in a weak magnetic field b) placing a magnetically hard material in a strong magnetic field c) placing a magnetically soft material in a weak magnetic field d) placing a magnetically soft material in a strong magnetic field

B) placing a magnetically hard material in a strong magnetic field

Explanation:

There are two type of magnetic materials in nature

1) Magnetic Hard materials

2) Magnetic soft materials

Here both materials are made up of domains which will not produce their own magnetic field due to their random arrangement

When we magnetize them by strong magnetic field then all domains will align themselves into the direction of magnetic field

Now if we use magnetic hard material then this alignment will last for long time but for magnetic soft material this alignment will change with time.

So in order to make strong permanent magnet the correct option would be

B) placing a magnetically hard material in a strong magnetic field

the results is a decrease in air temperature with an increase of altitude.

explanation:

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂