# Radioactivity vs K

The clearest difference is update cadence: K at every 2 weeks against Radioactivity's every 36 months. Radioactivity's advantage is iOS requirement (12.0 vs 17.0). On price, ads, in-app purchases and device support there is nothing between them.

Radioactivity costs $0.99 and K $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Radioactivity ships an update every 36 months, K every 2 weeks. The most recent releases landed on September 16, 2026 and September 21, 2026 respectively.

## The numbers

| Metric | Radioactivity | K |
| --- | --- | --- |
| Price | $0.99 | $0.99 |
| Positive reviews | — | 0.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 36 months | **Every 2 weeks** |
| Monetization | — | Paid |
| Size | 52 MB | 4 MB |
| Requires iOS | **12.0** | 17.0 |
| Devices | iPad | **iPhone, iPad** |
| Age rating | 4+ | 4+ |
| Developer | [www.ajaxmediatech.com](https://appshunter.io/developer/973768003) | [Masaki Kobayashi](https://appshunter.io/developer/1882180437) |

## What reviewers say

### Radioactivity

[App page](https://appshunter.io/ios/app/radioactivity-physics/id1136130171)

**Features:** macOS Compatibility

**In-app purchases:** none


### K

[App page](https://appshunter.io/ios/app/k-mol-molecular-model/id6772762907)

Create and visualize 2D and 3D molecular models with intuitive drawing tools and AR capabilities. This app serves as a practical and cost-effective alternative to physical model kits for students.

**Highlights:** 2D structural formula drawing, 3D molecular model visualization, Augmented Reality (AR) viewing, Save and reopen models, Pre-built templates, Screenshot capture

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Radioactivity free?

Radioactivity costs $0.99, with no in-app purchases.

### Is K free?

K costs $0.99, with no in-app purchases.

### Do Radioactivity or K have ads?

Neither Radioactivity nor K shows ads.

### Which is updated more often, Radioactivity or K?

Radioactivity ships an update every 36 months, and K every 2 weeks. Most recently, Radioactivity was updated on September 16, 2026 and K on September 21, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*