4. A
because PbCl2 is an ionic compound and it's solid, so it's a substance.
It cannot be mixture, because it's a pure molecule.
5. D
despite that both substances are gases, colorless they are different molecules, so they should have different either chemical and physical properties
6. C
this substance made from W atoms and others are made from molecules
<span>1)false a in chemical equilibrium concentration of reactant is equal to concentration of product
2)as here they said heat is added in product side means its endothermic reaction and in endothermic reaction on increasing temp. equilibrium shift towards forward direction so its true
3) B)as here mole are equal in reactant and product side that is 2 and if we increase pressure equilibrium shift in dat direction where no. of moles are less and here mole are equal so it will remain unaffected</span>
Atomic mass Sodium ( Na ) = 22.98 u.m.a
22.98 g ----------------- 6.02x10²³ atoms
175 g ------------------- ?? atoms
175 x ( 6.02x10²³) / 22.98 =
4.58x10²⁴ atoms of Na
hope this helps!
