Question

please choose best correct

11 The empirical formula for a compound that contained 14.4% hydrogen and 85.6% carbon by mass is CH CH; la 12 If The molecular weight of H,PO, is 97.9 g/mol, the Equivalent weight is.... a 32.6 g per equivalent | 49 g per equivalent b 98 g per equivalent a 196 g per equivalent 130.2 g/cm' is equivalent to a 2000 Kg/m € 200 kg/m b 2 Kg/m a 20 Kg/m 14 Convert 240 K and 19°F to the Celsius scale a 513°C and 292°C 33 °C and -13°C b|-33 °C and 108°C a|-33ºC and -7°C 15 How many atoms are there in 32 g of O,? (Avogadro's Number - 6.022 10) a 6.022 x 10 c 3.011 x 102 b 22.044 x 10 d None 16 Which of the following units is an SI unit? a Fahrenheit le Liter b Second a Milligram 17 Answer the following with the proper number of significant figures The sum of 6.079 +0.07772 +3.00 = a 9.15672 € 19.16 b 9.160 dl9.157 18 Molality unit is expressed as: a gram/liter Ic liter/mole b moles/liter d moles/1 kg solvent 19 How many phosphorus atoms are there in 2.57 g of P? a 1.55 x 10 | 10.00 x 10 b/7.00 x 10 Ja 5.00 x 10 |20 The measurement 0.000009901 m, expressed correctly using scientific notation, is m a 9.901 c 9.901 x 10m b 9.901 x 10 m a 19.901 x 10m

Answer 1

Solution:-

11.

Option d is correct

Note:-

Empirical formula     CH₂ (85.6% C; 14.4% H)

Molecular formula     C₄H₈

Option d is correct

12

Equivalent weight of H3PO4 is 49

Molar mass of H3PO4=[(3timesx 1)+31+(4times x 16)] =98g/mol

As, the replaceable hydrogen ions in acid is 2,

   

=98/2=49

Hence option c is correct .

13

0.2 g/cm3 is equivalent to 200 kg/m³

Option c is correct .

14

240K − 273.15 = -33.15°C

(19°F − 32) × 5/9 = -7.222°C

Hence option d is correct .

15

One mole of oxygen gas, which has the formula O₂, has a mass of 32 g and contains

One mole of atoms of oxygen has a mass of 16 g, as 16 is the atomic weight of oxygen, and contains 6.02 X 10²³ atoms of oxygen. One mole of oxygen gas, which has the formula O2, has a mass of 32 g and contains 6.02 X 10²³ molecules of oxygen

But 2 X 6.02 X 10²³ atoms is equal to 12.04 X 10²³, because each molecule of oxygen contains two oxygen atoms.

Hence correct option is d ie none

16

International System of Units is Second

The second (s), for time.

Hence correct option is b .