4 gm of NaOH is dissolved in 1000 ml of water. The ${\mathrm{H}}^{+}$ ion concentration will be:

Incorrect statement about pH and H⁺ is: 

If a solution of 0.1 N NH₄OH and 0.1 N NH₄Cl has pH 9.25, then pK_b of NH₄OH is:

1. 9.25

2. 4.75

3. 3.75

4. 8.25

What is the correct relationship between the pHs of isomolar solutions of sodium oxide (pH₁), sodium sulphide (pH₂), sodium selenide (pH₃), and sodium telluride (pH₄)?

1. ${\mathrm{pH}}_1<{\mathrm{pH}}_2<{\mathrm{pH}}_3<{\mathrm{pH}}_4$

2. ${\mathrm{pH}}_1>{\mathrm{pH}}_2>{\mathrm{pH}}_3>{\mathrm{pH}}_4$

3. ${\mathrm{pH}}_1<{\mathrm{pH}}_2<{\mathrm{pH}}_3\approx {\mathrm{pH}}_4$

4. ${\mathrm{pH}}_1>{\mathrm{pH}}_2\approx {\mathrm{pH}}_3>{\mathrm{pH}}_4$