by inserting in numerical sequence the following new heading: 9902.01.22 Nitrosylsulfuric acid (CAS. No. 7782–78–7) (provided for in subheading 2811.19.61) Free No change No change On or before 12/31/2020 . 24. Hypophosphorous acid 50% Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.23 Hypophosphorous acid 50% (phosphinic acid) (CAS No. 6303–21–5) (provided for in subheading 2811.19.61) Free No change No change On or before 12/31/2020 . 25. Sulfamic acid Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.24 Sulfamic acid (CAS No. 5329–14–6) (provided for in subheading 2811.19.61) Free No change No change On or before 12/31/2020 . 26. Hexafluorozirconic acid Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.25 Dihydrogen hexafluorozirconate(2-) (Hexafluorozirconic acid) (CAS No. 12021–95–3) (provided for in subheading 2811.19.61) Free No change No change On or before 12/31/2020 . 27. Certain spherical particles of silicon dioxide Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.26 Dioxosilane (Silicon dioxide amorphous) (CAS No. 7631-86-9) entirely spherical micro-spheres of mean particle size of 0.005 mm or smaller, uniform particle size with a uniformity coefficient of 1.65 or less, trace metal impurities less than 70 ppm, specific electrical resistance of 50,000 Ohm cm (provided for in subheading 2811.22.10) Free No change No change On or before 12/31/2020 . 28. Certain spherical particles of silicon dioxide Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.27 Dioxosilane (Silicon dioxide amorphous) (CAS No. 7631–86–9) entirely spherical micro-spheres of mean particle size of 0.005 mm or smaller, uniform particle size with a uniformity coefficient of 1.65 or less, trace metal impurities less than 70 ppm, specific